Dissertations / Theses on the topic 'Basal cell carcinoma'

The Aim of the project was to investigate cell senescence in basal cell carcinoma (BCC). Although the concept of oncogene-induced senescence (OIS) was originally confined to cultured cells, it is now well established that this mechanism has an important role in tumour biology. OIS represents a physiological response that restricts the progression of benign tumours into their malignant counterparts e.g. nevi to melanoma or adenoma to adenocarcinoma. Full malignancy is associated with the loss of important tumour suppressor genes including RETINOBLASTOMA and/or TP53. BCC of the skin is the most common skin tumour and is associated with mutational inactivation of the PTCH1 tumour suppressor gene (and less frequently oncogenic activation of SMOOTHENED). Although BCC does not appear to stem from precursor lesions - though mouse models of BCC display areas of basaloid hyperproliferation - and it is relatively stable at the genomic level, we sought to determine if these unique tumours display any characteristics of OIS. Human BCCs were positive for Senescence-associated β-galactosidase (SA-β-gal) activity (pH 6.0) and expressed known markers of senescence including DCR2, DEC1 (SHARP2) as well as the cell cycle inhibitors p15INK4b and p16INK4a. Interestingly, SA-β-gal activity was observed in stromal cells surrounding the tumour islands and this may account for why BCCs are difficult to culture in vitro as senescent cells are known to express increased levels of growth factors, cytokines and ECM proteins. To determine if OIS is associated with Hedgehog signalling in BCC, I employed a novel in vitro model of BCC created through PTCH1 suppression in human immortalised NEB1 keratinocytes. NEB1-shPTCH1 cells are viable and proliferative (albeit more slowly than control NEB1-shCON cells) and do not display SA-β-gal activity but they express higher levels of several senescent markers including DCR2 and p21WAF1. I also investigated senescence in a Mouse model of BCC in which one allele of Ptch1 is mutated and which on x-ray irradiation results in BCC formation. The expression of known markers of senescence including DCR2, DEC1 (SHARP2) as well as the cell cycle inhibitors p15INK4b, p16INK4a and p53 were all with the exception of p21WAF1 detected in these tumours. Together these data suggest that senescence is a characteristic of BCC and may explain why these tumours rarely metastasise.

Basal cell carcinoma (BCC) is a skin cancer of particular importance to the Australian community. Its rate of occurrence is highest in Queensland, where 1% to 2% of people are newly affected annually. This is an order of magnitude higher than corresponding incidence estimates in European and North American populations. Individuals with a sun-sensitive complexion are particularly susceptible because sun exposure is the single most important causative agent, as shown by the anatomic distribution of BCC which is in general consistent with the levels of sun exposure across body sites. A distinguishing feature of BCC is the occurrence of multiple primary tumours within individuals, synchronously or over time, and their diagnosis and treatment costs contribute substantially to the major public health burden caused by BCC. A primary knowledge gap about BCC pathogenesis however was an understanding of the true frequency of multiple BCC occurrences and their body distribution, and why a proportion of people do develop more than one BCC in their life. This research project sought to address this gap under an overarching research aim to better understand the detailed epidemiology of BCC with the ultimate goal of reducing the burden of this skin cancer through prevention. The particular aim was to document prospectively the rate of BCC occurrence and its associations with constitutional and environmental (solar) factors, all the while paying special attention to persons affected by more than one BCC. The study built on previous findings and recent developments in the field but set out to confirm and extend these and propose more adequate theories about the complex epidemiology of this cancer. Addressing these goals required a new approach to researching basal cell carcinoma, due to the need to account for the phenomenon of multiple incident BCCs per person. This was enabled by a 20 year community-based study of skin cancer in Australians that provided the methodological foundation for this thesis. Study participants were originally randomly selected in 1986 from the electoral register of all adult residents of the subtropical township of Nambour in Queensland, Australia. On various occasions during the study, participants were fully examined by dermatologists who documented cumulative photodamage as well as skin cancers. Participants completed standard questionnaires about skin cancer-related factors, and consented to have any diagnosed skin cancers notified to the investigators by regional pathology laboratories in Queensland. These methods allowed 100% ascertainment of histologically confirmed BCCs in this study population. 1339 participants had complete follow-up to the end of 2007. Statistical analyses in this thesis were carried out using SAS and SUDAAN statistical software packages. Modelling methods, including multivariate logistic regressions, allowed for repeated measures in terms of multiple BCCs per person. This innovative approach gave new findings on two levels, presented in five chapters as scientific papers: 1. Incidence of basal cell carcinoma multiplicity and detailed anatomic distribution: longitudinal study of an Australian population The incidence of people affected multiple times by BCC was 705 per 100,000 person years compared to an incidence rate of people singly affected of 935 per 100,000 person years. Among multiply and singly affected persons alike, site-specific BCC incidence rates were far highest on facial subsites, followed by upper limbs, trunk, and then lower limbs 2. Melanocytic nevi and basal cell carcinoma: is there an association? BCC risk was significantly increased in those with forearm nevi (Odds Ratios (OR) 1.43, 95% Confidence Intervals (CI) 1.09-1.89) compared to people without forearm nevi, especially among those who spent their time mainly outdoors (OR 1.6, 95%CI 1.1-2.3) compared to those who spent their time mainly indoors. Nevi on the back were not associated with BCC. 3. Clinical signs of photodamage are associated with basal cell carcinoma multiplicity and site: a 16-year longitudinal study Over a 16-year follow-up period, 58% of people affected by BCC developed more than one BCC. Among these people 60% developed BCCs across different anatomic sites. Participants with high numbers of solar keratoses, compared to people without solar keratoses, were most likely to experience the highest BCC counts overall (OR 3.3, 95%CI 1.4-13.5). Occurrences of BCC on the trunk (OR 3.3, 95%CI 1.4-7.6) and on the limbs (OR 3.7, 95%CI 2.0-7.0) were strongly associated with high numbers of solar keratoses on these sites. 4. Occurrence and determinants of basal cell carcinoma by histological subtype in an Australian community Among 1202 BCCs, 77% had a single growth pattern and 23% were of mixed histological composition. Among all BCCs the nodular followed by the superficial growth patterns were commonest. Risk of nodular and superficial BCCs on the head was raised if 5 or more solar keratoses were present on the face (OR 1.8, 95%CI 1.2-2.7 and OR 4.5, 95%CI 2.1-9.7 respectively) and similarly on the trunk in the presence of multiple solar keratoses on the trunk (OR 4.2, 95%CI 1.5-11.9 and OR 2.2, 95%CI 1.1-4.4 respectively). 5. Basal cell carcinoma and measures of cumulative sun exposure: an Australian longitudinal community-based study Dermal elastosis was more likely to be seen adjacent to head and neck BCCs than trunk BCCs (p=0.01). Severity of dermal elastosis increased on each site with increasing clinical signs of cutaneous sun damage on that site. BCCs that occurred without perilesional elastosis per se, were always found in an anatomic region with signs of photodamage. This thesis thus has identified the magnitude of the burden of multiple BCCs. It does not support the view that people affected by more than one BCC represent a distinct group of people who are prone to BCCs on certain body sites. The results also demonstrate that BCCs regardless of site, histology or order of occurrence are strongly associated with cumulative sun exposure causing photodamage to the skin, and hence challenge the view that BCCs occurring on body sites with typically low opportunities for sun exposure or of the superficial growth pattern are different in their association with the sun from those on typically sun-exposed sites, or nodular BCCs, respectively. Through dissemination in the scientific and medical literature, and to the community at large, these findings can ultimately assist in the primary and secondary prevention of BCC, perhaps especially in high-risk populations.

Basal cell carcinoma (BCC) is the most common skin cancer in humans. The demonstration of genetic and protein alterations has, so far, had limited correlation with either biological behaviour or histological classification of these tumours. It was observed that Glil-overexpressing keratinocytes express elevated levels of genes known to be associated with neuronal development, including p-tubulin III, GAP-43, Arc and neurofilament. It was proposed that these genes may similarly be overexpressed in BCCs and that different levels of expression may be present in different BCC subtypes Immunohistochemistry of BCCs demonstrated that neuronal differentiation marker proteins are expressed in BCCs, but that this expression is significantly reduced in tumours that behave aggressively. Elevated neuronal differentiation marker gene expression was shown in BCCs. Again, expression was more prominent in tumour types that behave indolently. Results were obtained for tumour samples processed by laser capture microdissection, needle microdissection and homogenised tissue. Expression of neuronal differentiation marker genes in Gli-overexpressing keratinocytes was examined by semi-quantitiative PCR. Neuronal differentiation marker expression was associated with GUI and GH2 over-expression in some cases {P-tubulin III and Arc). GUI and GH2 also promoted the expression of each other in a positive-feedback loop. Expression of these markers was examined in archival tumours for which the clinical outcome was known in terms of recurrence. In completely excised tumours P-tubulin III was significantly reduced in tumours that went on to subsequently recur. Other markers were not expressed in significantly different amounts. In summary, I have shown that expression of markers associated with neuronal development is a feature of Basal Cell carcinoma, and that the expression of these markers correlates strongly with the tumour histological subtype but only weakly with tumour recurrence. More work will be required to discover further alterations in BCC molecular biology that impact significantly on tumour behaviour.

Basal cell carcinoma (BCC) is the most common type of skin cancer which arises in the skin’s basal cells that line the deepest layer of the epidermis. Previous studies have identified some immune privilege (IP) related genes and products expressed in some malignancies. IP is also believed to exist in BCC tumors during BCC development. However, quantitative analyses and functional studies to clearly demonstrate IP in BCC tumors are required. My goal was to examine BCC tumor cells to identify novel functional mechanisms of IP. My hypothesis was that BCC tumors have functional IP capabilities. With in vitro experiments, I found that cultured BCC cells appeared to suppress histo-incompatible peripheral blood mononuclear cell (PBMC) T cells’ activation, as well as IFN-γ secretion. In contrast, non-tumor skin cells from the same subject elicited significant T cell activation. I screened for expression of candidate IP-related genes in BCC tumors relative to normal skin from healthy people by quantitative RT-PCR. I found significant upregulation of CD200, and a downregulation of its receptor CD200R. There were also several other genes related to IP expressed differently in BCC tumors compared to healthy control tissues. We also demonstrated the upregulation of CD200 and downregulation of CD200R at the protein level by flow cytometry. In summary, these experiments give further evidence in support of BCC IP and predict a potential role of CD200 in BCC IP.
Medicine, Faculty of
Experimental Medicine, Division of
Medicine, Department of
Graduate

BCC is the commonest cancer in European-derived populations and Australia has the highest recorded incidence in the world, creating enormous individual and societal cost in management of this disease. The incidence of this cancer has been increasing internationally, with evidence of a 1 to 2% rise in incidence in Australia per year over the last two decades. The main four epidemiological risk factors for the development of BCC are ultraviolet radiation (UVR) exposure, increasing age, male sex, and inability to tan. The pattern and timing of UVR exposure is important to BCC risk, with childhood and intermittent UVR exposure both associated with an increased risk. The complex of inherited characteristics making up an individual’s ‘sun sensitivity’ is also important in determining BCC risk. Very little is known about population genetic susceptibility to BCC outside of the rare genodermatosis Gorlin syndrome. Mutations in the tumour suppressor gene patched (PTCH) are responsible for this BCC predisposition syndrome and the molecular pathway and target genes of this highly conserved pathway are well described. Derangments in this pathway occur in sporadic BCC development, and the PTCH gene is an obvious candidate to contribute to non-syndromic susceptibility to BCC. The melanocortin 1 receptor (MC1R) locus is known to be involved in pigmentary traits and the cutaneous response to UVR, and variants have been associated with skin cancer risk. Many other genes have been considered with respect to population BCC risk and include p53, HPV, GSTs, and HLAs. There is preliminary evidence for specific familial aggregation of BCC, but very little known about the causes. 56 individuals who developed BCC under the age of 40 in the year 2000 were recruited from the Skin and Cancer Foundation of Australia’s database. This represents the youngest 7 – 8% of Australians with BCC from a database that captures approximately 10% of Sydney’s BCCs. 212 of their first degree relatives were also recruited, including 89 parents and 123 siblings of these 56 probands. All subjects were interviewed with respect to their cancer history and all reports of cancer verified with histopathological reports where possible. The oldest unaffected sibling for each proband (where available) was designated as an intra-family control. All cases and control siblings filled out a questionnaire regarding their pigmentary and sun sensitivity factors and underwent a skin examination by a trained examiner. Peripheral blood was collected from these cases and controls for genotyping of PTCH. All the exons of PTCH for which mutations have been documented in Gorlin patients were amplified using PCR. PCR products were screened for mutations using dHPLC, and all detectable variants sequenced. Prevalence of BCC and SCC for the Australian population was estimated from incidence data using a novel statistical approach. Familial aggregation of BCC, SCC and MM occurred within the 56 families studied here. The majority of families with aggregation of skin cancer had a combination of SCC and BCC, however nearly one fifth of families in this study had aggregation of BCC to the exclusion of SCC or MM, suggesting that BCCspecific risk factors are also likely to be at work. Skin cancer risks for first-degree relatives of people with early onset BCC were calculated: sisters and mothers of people with early-onset BCC had a 2-fold increased risk of BCC; brothers had a 5-fold increased risk of BCC; and sisters and fathers of people with early-onset BCC had over four times the prevalence of SCC than that expected. For melanoma, the increased risk was significant for male relatives only, with a 10-fold increased risk for brothers of people with early-onset BCC and 3-fold for fathers. On skin examination of cases and controls, several phenotypic factors were significantly associated with BCC risk. These included increasing risk of BCC with having fair, easyburning skin (ie decreasing skin phototype), and with having signs of cumulative sun damage to the skin in the form of actinic keratoses. Signs reflecting the combination of pigmentary characteristics and sun exposure - in the form of arm freckling and solar lentigines - also gave subjects a significantly increased risk BCC. Constitutive red-green reflectance of the skin was associated with decreased risk of BCC, as measured by spectrophotometery. Other non-significant trends were seen that may become significant in larger studies including associations of BCC with propensity to burn, moderate tanning ability and an inability to tan. No convincing trend for risk of BCC was seen with the pigmentary variables of hair or eye colour, and a non-significant reduced risk of BCC was associated with increasing numbers of seborrhoeic keratoses. Twenty PTCH exons (exons 2, 3, 5 to 18, and 20 to 23) were screened, accounting for 97% of the coding regions with published mutations in PTCH. Nine of these 20 exons were found to harbour single nucleotide polymorphisms (SNPs), seen on dHPLC as variant melting curves and confirmed on direct sequencing. SNPs frequencies were not significantly different to published population frequencies, or to Australian general population frequencies where SNP database population data was unavailable. Assuming a Poisson distribution, and having observed no mutations in a sample of 56, we can be 97.5% confident that if there are any PTCH mutations contributing to early-onset BCC in the Australian population, then their prevalence is less than 5.1%. Overall, this study provides evidence that familial aggregation of BCC is occurring, that first-degree relatives are at increased risk of all three types of skin cancer, and that a combination of environmental and genetic risk factors are likely to be responsible. The PTCH gene is excluded as a major cause of this increased susceptibility to BCC in particular and skin cancer in general. The weaknesses of the study design are explored, the possible clinical relevance of the data is examined, and future directions for research into the genetics of basal cell carcinoma are discussed.

Doctor of Philosophy(PhD)
BCC is the commonest cancer in European-derived populations and Australia has the highest recorded incidence in the world, creating enormous individual and societal cost in management of this disease. The incidence of this cancer has been increasing internationally, with evidence of a 1 to 2% rise in incidence in Australia per year over the last two decades. The main four epidemiological risk factors for the development of BCC are ultraviolet radiation (UVR) exposure, increasing age, male sex, and inability to tan. The pattern and timing of UVR exposure is important to BCC risk, with childhood and intermittent UVR exposure both associated with an increased risk. The complex of inherited characteristics making up an individual’s ‘sun sensitivity’ is also important in determining BCC risk. Very little is known about population genetic susceptibility to BCC outside of the rare genodermatosis Gorlin syndrome. Mutations in the tumour suppressor gene patched (PTCH) are responsible for this BCC predisposition syndrome and the molecular pathway and target genes of this highly conserved pathway are well described. Derangments in this pathway occur in sporadic BCC development, and the PTCH gene is an obvious candidate to contribute to non-syndromic susceptibility to BCC. The melanocortin 1 receptor (MC1R) locus is known to be involved in pigmentary traits and the cutaneous response to UVR, and variants have been associated with skin cancer risk. Many other genes have been considered with respect to population BCC risk and include p53, HPV, GSTs, and HLAs. There is preliminary evidence for specific familial aggregation of BCC, but very little known about the causes. 56 individuals who developed BCC under the age of 40 in the year 2000 were recruited from the Skin and Cancer Foundation of Australia’s database. This represents the youngest 7 – 8% of Australians with BCC from a database that captures approximately 10% of Sydney’s BCCs. 212 of their first degree relatives were also recruited, including 89 parents and 123 siblings of these 56 probands. All subjects were interviewed with respect to their cancer history and all reports of cancer verified with histopathological reports where possible. The oldest unaffected sibling for each proband (where available) was designated as an intra-family control. All cases and control siblings filled out a questionnaire regarding their pigmentary and sun sensitivity factors and underwent a skin examination by a trained examiner. Peripheral blood was collected from these cases and controls for genotyping of PTCH. All the exons of PTCH for which mutations have been documented in Gorlin patients were amplified using PCR. PCR products were screened for mutations using dHPLC, and all detectable variants sequenced. Prevalence of BCC and SCC for the Australian population was estimated from incidence data using a novel statistical approach. Familial aggregation of BCC, SCC and MM occurred within the 56 families studied here. The majority of families with aggregation of skin cancer had a combination of SCC and BCC, however nearly one fifth of families in this study had aggregation of BCC to the exclusion of SCC or MM, suggesting that BCCspecific risk factors are also likely to be at work. Skin cancer risks for first-degree relatives of people with early onset BCC were calculated: sisters and mothers of people with early-onset BCC had a 2-fold increased risk of BCC; brothers had a 5-fold increased risk of BCC; and sisters and fathers of people with early-onset BCC had over four times the prevalence of SCC than that expected. For melanoma, the increased risk was significant for male relatives only, with a 10-fold increased risk for brothers of people with early-onset BCC and 3-fold for fathers. On skin examination of cases and controls, several phenotypic factors were significantly associated with BCC risk. These included increasing risk of BCC with having fair, easyburning skin (ie decreasing skin phototype), and with having signs of cumulative sun damage to the skin in the form of actinic keratoses. Signs reflecting the combination of pigmentary characteristics and sun exposure - in the form of arm freckling and solar lentigines - also gave subjects a significantly increased risk BCC. Constitutive red-green reflectance of the skin was associated with decreased risk of BCC, as measured by spectrophotometery. Other non-significant trends were seen that may become significant in larger studies including associations of BCC with propensity to burn, moderate tanning ability and an inability to tan. No convincing trend for risk of BCC was seen with the pigmentary variables of hair or eye colour, and a non-significant reduced risk of BCC was associated with increasing numbers of seborrhoeic keratoses. Twenty PTCH exons (exons 2, 3, 5 to 18, and 20 to 23) were screened, accounting for 97% of the coding regions with published mutations in PTCH. Nine of these 20 exons were found to harbour single nucleotide polymorphisms (SNPs), seen on dHPLC as variant melting curves and confirmed on direct sequencing. SNPs frequencies were not significantly different to published population frequencies, or to Australian general population frequencies where SNP database population data was unavailable. Assuming a Poisson distribution, and having observed no mutations in a sample of 56, we can be 97.5% confident that if there are any PTCH mutations contributing to early-onset BCC in the Australian population, then their prevalence is less than 5.1%. Overall, this study provides evidence that familial aggregation of BCC is occurring, that first-degree relatives are at increased risk of all three types of skin cancer, and that a combination of environmental and genetic risk factors are likely to be responsible. The PTCH gene is excluded as a major cause of this increased susceptibility to BCC in particular and skin cancer in general. The weaknesses of the study design are explored, the possible clinical relevance of the data is examined, and future directions for research into the genetics of basal cell carcinoma are discussed.

Abnormal Sonic Hedgehog (SHH) signalling leads to increased transcriptional activation of its downstream effector, GLI2, which is implicated in the pathogenesis of a variety of human tumours, including human basal cell carcinoma (BCC). However, little is known about the molecular mechanisms underlying the tumourigenic role of GLI2 in human skin keratinocytes. This study examines the effects of inducible and stable expression of constitutively active GLI2 (GLI2:N) oncogenic transcription factor, on immortalised human epidermal keratinocytes. It is shown here that GLI2:N overexpressing N/TERT keratinocytes display gene expression patterns and phenotypic characteristics reminiscent of those observed in human BCC in vivo. It is also shown for first time, that expression of GLI2:N in N/TERT keratinocytes is sufficient to induce accumulation of binucleated/tetraploid cells as evidenced by an increase in G2/M phase of the cell cycle and binucleate cell counting, and to promote polyploidy and aneuploidy, in the absence of increased cell death or apoptosis. This cell cycle deregulation is accompanied by strong activation of anti-apoptotic protein BCL-2 and simultaneous suppression of important cell-cycle regulators such as 14-3-3σ and CDK inhibitor p21WAF1/CIP1, with no change in p53 protein levels, indicating uncontrolled proliferation of cells with ploidy abnormalities and/or DNA damage. Consistently, it is shown that p21WAF1/CIP1 protein is also absent in human BCC tumours and that forced overexpression of GLI2:N renders human keratinocytes resistant to apoptosis mediated by ultraviolet B (UVB, 290-320 nm), one of the most important etiological factors in BCC formation. Karyotype analysis of GLI2:N N/TERT keratinocytes further demonstrates that overexpression of GLI2:N induces numerical (tetraploidy, polyploidy, aneuploidy) and structural instability in N/TERT keratinocytes including chromosomal translocations and double minute chromosomes. Furthermore, β-catenin activation is the most common alteration observed during aberrant WNT signalling, and is often implicated in the development of human carcinogenesis and metastasis. In this study it is shown that GLI2:N induction induces nuclear accumulation of β-catenin in keratinocyte cell culture and in the basal layer of organotypic skin rafts, similar to human BCCs. In addition, several WNT genes were found to be upregulated upon GLI2:N induction, while β-catenin transcriptional activity is increased upon stable and conditional expression of GLI2:N. Overall these data give new insights for the possible mechanisms that mediate the tumourigenic potential of GLI2.

Background: Superficial basal cell carcinoma (sBCC) can be safely treated topically. Potentially, non-invasive imaging techniques, such as optical coherence tomography (OCT), may be useful to diagnose sBCC without biopsy. Objective: To evaluate OCT’s 1) sensitivity and specificity for sBCC diagnosis 2) accuracy in determining BCC depth Methods: A prospective, consecutive cohort of lesions for which sBCC was considered in the differential diagnosis underwent clinical, dermoscopic and OCT assessment. Diagnosis and its confidence were recorded for each modality and correlated with the histopathological diagnosis. Interpretation of the OCT images was performed blinded to the biopsy results. Results: 168 lesions were recruited. 52% were sBCC, 26% were other BCC variants and the remaining lesions were actinic keratoses, squamous cell carcinoma in-situs, other benign inflammatory processes, and other malignant tumours. Sensitivity and specificity of OCT for diagnosis of sBCC were 0.87 and 0.80, respectively. There was excellent correlation between OCT and biopsy for tumour depth amongst tumours ≤0.4mm (Pearson’s correlation r=0.86, p<0.001) but correlation was less as depth increased (Pearson’s correlation r=0.71, p<0.001 for all tumours <1.0mm). Conclusions: OCT has good diagnostic accuracy for diagnosing sBCC and measuring depth in tumours ≤0.4mm and can reduce the need for biopsy in clinically-suspected sBCCs.

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 51).
In this thesis we explore different machine learning techniques that are common in image classification to detect the presence of Basal Cell Carcinoma (BCC) in digital skin histological images. Since digital histology images are extremely large, we first focused on determining the presence of BCC at the patch level, using pre-trained deep convolutional neural networks as feature extractors to compensate for the size of our datasets. The experimental results show that our patch level classifiers obtained an area under the receiver operating characteristic curve (AUC) of 0.981. Finally, we used our patch classifiers to generate a bag of scores for a given whole slide image (WSI), and attempted multiple ways of combining these scores to produce a single significant score to predict the presence of BCC in the given WSI. Our best performing model obtained an AUC of 0.991 in 86 samples of digital skin biopsies, 43 of which had BCC.
by Tomás Alberto Calderón Gómez.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

Despite the ability to modulate SHH signalling, EGF pathway inhibitors targeting pAKT and pERK may not be useful for treating basal cell carcinoma. Alternative SHH signalling inhibitors such as those that target the formation of the primary cilium may be highly effective.

Purpose: Automatic border detection is the first and most crucial step for lesion segmentation and can be very challenging, due to several lesion characteristics. There are many melanoma border-detecting algorithms that perform poorly on dermoscopy images of basal cell carcinoma (BCC), which is the most common skin cancer. One of the reasons for poor lesion detection performance is that there are very few algorithms that detect BCC borders, because they are difficult to segment, even for dermatologists. This difficulty is due to low contrast, variation in lesion color and artifacts inside/outside the lesion. Segmentation that has adequate lesion-feature capture, with acceptable tolerance, will facilitate accurate feature segmentation, thereby maximizing classification accuracy. Methods: The main objective of this research was to develop an effective BCC border detecting algorithm whose accuracy is better than the existing melanoma border detectors that have been applied to BCCs. Fifteen auto-thresholding techniques were implemented for BCC lesion segmentation; but, only five were selected for use in algorithm development. A novel technique was developed to automatically expand BCC lesion borders, to completely circumscribe the lesion. Two error metrics were used that better measure Type II (false-negative) errors: Relative XOR error and Lesion Capture Ratio (a novel error metric). Results: On training and test sets of 1023 and 119 images, respectively, based on two error metrics, five thresholding-based algorithms outperformed two state-of-the-art melanoma segmentation techniques, in segmenting BCCs. Five algorithms generated borders that appreciably better matched dermatologists’ hand-drawn borders which were used as the “gold standard.” Conclusion: The five developed algorithms, which included solutions for image-vignetting correction and border expansion, to achieve dermatologist-like borders, provided more inclusive and therefore, feature-preserving border detection, favoring better BCC classification accuracy, for future work.

Skin cancers are very common in humans. The two most frequent epithelial skin cancers are the basal cell carcinoma (BCC) and the squamous cell carcinoma (SCC). For the vast majority of cancers, the cell at the origin of tumour initiation is still unknown and assumptions concerning their origin rely mainly on morphological and immunohistochemical studies. Recently, adult stem cells (SCs) have been suggested to be at the origin of tumour initiation based on their long term self-renewing capacities. According to these, two important questions arise; do epithelial skin cancers arise from mutations in a specific cell lineage of the epidermis? And are the stem cells more competent to initiate tumors than committed cells?

BCCs result from aberrant activation of HH signaling and several mouse models carrying mutations in HH signaling genes are capable to form tumors resembling to human BCCs.

To identify the cell lineage at the origin of BCC and to investigate the role of stem cells in tumor initiation, we followed a genetic approach where we conditionally expressed SmoM2 oncogene (a constitutively active Smoothened mutant) in distinct skin epidermal compartments including SCs. Targeting basal epidermis cells, showed that only SmoM2-clones in the inter follicular epidermis (IFE) and the infundibulum can progress into BCC, whereas SmoM2 expression in Bulge SCs or in matrix transit amplifying progenitor cells never leads to BCC formation. Progressively after SmoM2 expression, tumor-initiating cells lose their normal differentiation to adopt a hair placode-like shape and markers, demonstrating that biochemical and morphological tumour features can be misleading in extrapolating their cellular origin.

The molecular changes occurring in tumor initiating cells and the mechanisms regulating the early steps of cancer development are poorly characterized for the majority of tumors. To address these questions in BCC, we took advantage of our ability to isolate SmoM2 expressing cells at different stages of tumor initiation and progression. Transcriptional profiling of SmoM2-basal IFE cells isolated one week (normal histology) and 4 weeks (dysplastic lesion), suggests that adult IFE cells undergo a reprogramming into embryonic hair follicle (EHFP) like fate. In addition, we showed that Wnt/β-catenin signaling is essential for BCC initiating cell reprogramming into EHFP like fate and for tumor initiation in a cell autonomous manner. Finally, we show that EHFP reprogramming occurs also in human BCCs in addition to the presence of a similar canonical Wnt activation signature to the one revealed in the SmoM2-BCC mouse model.

SCC is the second most frequent skin cancers after BCC and mutations in p53 and Ras genes has been suggested to be potentially the primary events in this tumour. SCCs present signs of squamous differentiation, suggesting that SCCs may originate from the inter follicular epidermis (IFE). To identify the cell lineage at the origin of SCC and the role of the hair follicle SCs in tumor initiation, we use a genetic tools driving oncogenic KRas (KRasG12D) expression at physiological levels in different epidermal compartments.

Targeting KRasG12D expression in bulge SCs and their progeny or in IFE results in benign tumor development with no sign of malignant transformation. In contrast, KRasG12D expression in HF Transit amplifying (TA) matrix cells do not promotes any macroscopic tumors or microscopic defects in the epidermis. Interestingly, papillomas arising from the IFE express follicular markers such as CD34 and K17, indicating that the expression of HF markers by tumor cells does not necessarily reflect their cellular origin. Using a combination of deletion of both p53 alleles together with KRasG12D expression, we showed that bulge SCs and/or their progeny but not HF matrix TA cells, promote SCC formation, suggesting that additional genetic hits such as p53 are required to promote full-blown invasive skin SCC.

In summary, our work demonstrated the non-follicular origin of BCC resulting from Smo mutation, as well as the implication of the IFE progenitors in tumor initiation. We also revealed the progressive reprogramming of BCC initiating cells towards an EHFP-like fate and the key role of Wnt/β-catenin pathway in this process. In contrast, we showed the competence of several epidermal lineages to initiate benign tumors upon expression of KRasG12D oncogene at physiological levels. We also demonstrated that lineage -specific markers expression within tumor cells does not necessarily reflect their cellular origin. Finally, we demonstrated the requirement of additional hits, such as P53 loss, to promote malignant progression in the context of oncogenic Ras.

Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished

Periocular malignancy represents an increasing burden and currently requires disfiguring surgery in an attempt to cure patients. Basal cell carcinoma (BCC) is the commonest cancer worldwide and morphoeic BCC (mBCC) is an aggressive subtype. Sebaceous gland carcinoma (SGC) is a rare, but life-threatening condition that often requires blinding surgery to prevent mortality, especially in the pagetoid subtype. MBCC has a high risk of local recurrence compared to the more indolent nodular subtype reflected by a different set of driver genes including FLNB and HECTD4. Surrounding mBCC stroma is abnormal, containing mutations in EPHA3 and GLI3. Four common dysregulated pathways detected using both whole exome and RNA sequencing for mBCC were; 'hedgehog (Hh) signalling pathway', 'BCC', 'Natural killer cell mediated cytotoxicity' and 'Fc Epsilon RI signalling pathway'. Hh mutational profile for nodular BCC was not reflected in the RNA and protein expression. In contrast, Hh overexpression is seen in the tumour and stroma of morphoeic tissue with the latter potentially being partly responsible for its aggressive nature and risk of recurrence that may warrant removal to prevent recurrence. SGC has a low overall mutational burden, no UV signature and defective mismatch repair signature. Driver genes included TP53, RB1 and the dynein family is a novel driver possibly involved in chromatid segregation as marked chromosomal instability was demonstrated on copy number analysis. Correlation of whole exome and RNA sequencing data demonstrated upregulated 'cell cycle', 'ubiquitin mediated proteolysis' and 'wnt signalling'. Subtype analysis of pagetoid and nodular SGC revealed the histone gene cluster family as important to both. Oncomir hsa-miR-21 was overexpressed in both and loss of hsa-miR-199a occurs in pagetoid. Increased protein expression of HIST1H2BD was seen in both subtypes as was Hh expression. These novel SGC findings support a chromosomally unstable cancer with the ability to invade extracellular matrix.

Introducció: Els carcinomes de queratinòcits (CQ) són la neoplàsia maligna més freqüent a nivell mundial en poblacions caucàsiques. En conjunt, suposen un enorme problema de salut, tant en termes de morbiditat com de despesa sanitària. En les darreres dècades, la seva incidència ha augmentat de manera significativa. A més a mes, pel que fa al carcinoma basocel·lular (CBC), han augmentat dramàticament els casos entre la gent jove, sobretot dones. Els CQ tenen, en general, un bon pronòstic. Malgrat això, el CBC pot créixer localment destruint els teixits circumdants i causant importants seqüeles funcionals i estètiques, i el carcinoma escatós (CEC) és moderadament invasiu i es pot associar a un risc substancial de recurrències locals, metàstasis i mort (1.5-4 %). La fisiopatologia dels CQ és dependent de l’alteració de diverses vies de transducció de senyals i de control de la proliferació. Un dels efectes d’aquestes alteracions és la secreció de noves proteïnes a l’espai extracel·lular, que caracteritzaran el microambient tumoral. Les proteïnes i metabòlits senyalitzadors presents en el fluid intersticial que envolta el tumor (TIF) han estat estudiats en alguns tipus tumorals, però no hi ha res descrit pel que fa als CQ. Objectius: Aquesta tesi té dos objectius principals: 1) Estudi epidemiològic i de factors de risc del CBC a Catalunya (Capítol I), i 2) Caracteritzar el perfil proteòmic del TIF en els CQ i les implicacions en la seva fisiopatologia (Capítols II i III). Resultats i conclusions: En l’estudi epidemiològic hem observat que entre els < 60 anys el CBC ja és un tumor que té una incidència major en dones que en homes. Els factors de risc independents pel CBC en gent jove són el fototipus cutani, la història familiar de CQ, i la presència de ≥ 4 cremades a la infància. A més a més, la presència de repetides cremades a la infància és superior entre els casos de CBC en gent jove localitzats en zones cobertes que entre els localitzats en zones fotoexposades. De tots els factors de risc, entre la població general, l’ús de cabines de bronzejat és l’únic que és més freqüent entre les dones que entre els homes; per tant, la popularització del seu ús podria ser la causa de la tendència a la predominança femenina del CBC. En la segona part de la tesi, primer s’ha posat a punt el mètode d’aïllament de TIF. La centrifugació a 10 000 g permet obtenir una quantitat superior de proteïnes extracel·lulars, major sensibilitat i un maneig més ràpid i fàcil de les mostres, sense implicar un augment de la lisi cel·lular respecte als altres mètodes. Per aquests motius, la proposem com a mètode d’elecció en les mostres de tumors cutanis. L’anàlisi proteòmica mostra que el CBC, el CEC i la pell sana tenen cadascun un perfil específic de proteïnes secretades al seu TIF i suggereix l’existència d’una diferent resposta immunològica de l’organisme en front al CBC i al CEC. Hem determinat que la secreció de les proteïnes PNP, FABP5, SFN i LAD1 és un perfil propi del CEC, i que estan relacionades amb l’agressivitat tumoral i podrien ser dianes terapèutiques per al seu tractament. A més a més, el patró d’expressió de FABP5 permet distingir les zones diferenciades de les invasives en el CEC. També existeix una diferent localització cel·lular de l’SFN i la LAD1 en la pell sana vs. CEC, que podria estar relacionada amb el desenvolupament tumoral. Finalment, la secreció de cornulina és un marcador de CBC i tendeix a associar-se amb els subtipus més agressius.
Introducción: Los carcinomas de queratinocitos (CQ) son la neoplasia maligna más frecuente a nivel mundial en poblaciones caucásicas. En conjunto, suponen un enorme problema de salud, tanto en términos de morbilidad como de gasto sanitario. En las últimas décadas, su incidencia ha aumentado de manera significativa. Además, en el carcinoma basocelular (CBC), han aumentado dramáticamente los casos entre la gente joven, sobre todo mujeres. Los CQ tienen, en general, un buen pronóstico. A pesar de ello, el CBC puede crecer localmente destruyendo los tejidos circundantes y causar importantes secuelas funcionales y estéticas, y el carcinoma escamoso (CEC) es moderadamente invasivo y se puede asociar a un riesgo sustancial de recurrencias locales, metástasis y muerte (1.5-4 %). La fisiopatología de los CQ es dependiente de la alteración de varias vías de transducción de señales y de control de la proliferación. Uno de los efectos de estas alteraciones es la secreción de nuevas proteínas en el espacio extracelular, que caracterizarán el microambiente tumoral. Las proteínas y metabolitos señalizadores presentes en el fluido intersticial que rodea el tumor (TIF) han sido estudiados en algunos tipos tumorales, pero no hay nada descrito en cuanto a CQ. Objetivos: Esta tesis tiene dos objetivos principales: 1) Estudio epidemiológico y de factores de riesgo del CBC en Cataluña (Capítulo I), y 2) Caracterizar el perfil proteómico del TIF en los CQ y las implicaciones en su fisiopatología (Capítulos II y III). Resultados y conclusiones: En el estudio epidemiológico se ha observado que entre los < 60 años el CBC ya es un tumor que tiene una incidencia mayor en mujeres que en hombres. Los factores de riesgo independientes para el CBC en gente joven son el fototipo cutáneo, la historia familiar de CQ, y la presencia de ≥ 4 quemaduras en la infancia. Además, la presencia de repetidas quemaduras en la infancia es superior entre los casos de CBC en gente joven localizados en zonas cubiertas que entre los localizados en zonas fotoexpuestas. De todos los factores de riesgo, en la población general, el uso de cabinas de bronceado es el único que es más frecuente entre las mujeres que entre los hombres; por lo tanto, la popularización de su uso podría ser la causa de la tendencia a la predominancia femenina del CBC. En la segunda parte de la tesis, primero se ha puesto a punto el método de aislamiento de TIF. La centrifugación a 10 000 g permite obtener una cantidad superior de proteínas extracelulares, mayor sensibilidad y un manejo más rápido y fácil de las muestras, sin implicar un aumento de la lisis celular respecto a los otros métodos. Por estos motivos, la proponemos como método de elección en las muestras de tumores cutáneos. El análisis proteómico muestra que el CBC, el CEC y la piel sana tienen cada uno un perfil específico de proteínas secretadas en su TIF y sugiere la existencia de una diferente respuesta inmunológica del organismo frente al CBC y al CEC. Hemos determinado que la secreción de las proteínas PNP, FABP5, SFN y LAD1 es un perfil propio del CEC, y que están relacionadas con la agresividad tumoral y podrían ser dianas terapéuticas para su tratamiento. Además, el patrón de expresión de FABP5 permite distinguir las zonas diferenciadas de las invasivas en el CEC. También existe una diferente localización celular de la SFN y la LAD1 en la piel sana vs. CEC, que podría estar relacionada con el desarrollo tumoral. Finalmente, la secreción de cornulina es un marcador de CBC y muestra tendencia a asociarse con los subtipos más agresivos.
Introduction: Keratinocyte carcinomas (KC) are the most frequent malignancy in Caucasian populations worldwide. Altogether, they entail a huge health problem, both in terms of morbidity and health costs. In recent decades, their incidence has increased significantly. Moreover, basal cell carcinoma (BCC) cases have increased dramatically among young people, especially women. KC generally have a good prognosis. Despite this, BCC can grow locally, destroying surrounding tissues and causing important functional and aesthetic sequelae; and squamous cell carcinoma (SCC) is moderately invasive and can be associated with a substantial risk of local recurrences, metastasis, and death (1.5- 4 %). The physiopathology of KC depends on the alteration of several signal transduction pathways and proliferation control. One effect of these alterations is the secretion of new proteins in the extracellular space, which will characterize the tumor microenvironment. The signaling proteins and metabolites present in the interstitial fluid surrounding the tumor (TIF) have been studied in some tumor types, but nothing has been described in terms of KC. Objectives: This thesis has two main objectives: 1) Epidemiological and risk factors study of BCC in Catalonia (Chapter I), and 2) Characterization of the proteomic profile of TIF in KC and the implications in their physiopathology (Chapters II and III). Results and conclusions: In the epidemiological study, it has been revealed that, among those <60 years, BCC is already a tumor that has a higher incidence in women than in men. Independent risk factors for BCC in young people are skin phototype, family history of KC, and the presence of ≥ 4 sunburns in childhood. In addition, the presence of repeated sunburns in childhood is higher among BCC cases in young people in covered areas than among those in photo-exposed areas. Of all the risk factors, among the general population, the use of tanning beds is the only one that is more common among women than among men; therefore, the popularization of their use could be the crucial factor for the trend towards the female predominance of BCC. In the second part of the thesis, the TIF isolation method has been first developed. Centrifugation at 10 000 g allows obtaining a higher amount of extracellular proteins, greater sensitivity, and faster and easier handling of the samples, without increasing cell lysis when compared to other methods. For these reasons, we propose it as the method of choice in samples of skin tumors. The proteomic analysis shows that BCC, SCC, and healthy skin each have a specific profile of secreted proteins in their TIF, and suggests the existence of a different immune response of the organism against BCC and SCC. We have determined that the secretion of PNP, FABP5, SFN, and LAD1 proteins is a specific SCC profile, and that they are related to tumor aggressiveness and could be therapeutic targets for its treatment. Furthermore, the expression pattern of FABP5 makes it possible to distinguish differentiated from invasive areas in SCC. There is also a different cellular location of SFN and LAD1 expression in healthy skin vs. SCC, which could be related to tumor development. Finally, cornulin secretion is a BCC marker and tends to associate with the most aggressive subtypes.

Background. Both basal-like subtype and BRCA1-related breast cancers tend to have a poor overall prognosis and lack of effective treatments. Given that the lung cancer drug gefitinib and the leukemia drug dasatinib inhibit proteins also belonging to the molecular signature of this subtype, we and others hypothesized that they might be useful therapies for those two breast cancer subgroups.
Methods. Eight breast cancer cell lines were characterized by immunohistochemistry and western blotting and were treated with both drugs. Response was measured by using the sulphorhodamine B (SRB) assay.
Results. Two out of six basal-like cell lines were sensitive to gefitinib and five of six to dasatinib. BRCA1-related breast cancers were also responsive to dasatinib (three out of four). Moreover, EGFR and caveolin-1 act as markers for dasatinib sensitivity, but do not appear to be the primary targets of this drug. The presence of SRC but not ABL is necessary to achieve a response to dasatinib.
Conclusion. Dasatinib is more effective in the treatment of basal-like breast cancers than gefitinib and acts by inhibiting SRC and other molecules that are yet to be determined.

Topical photodynamic therapy (PDT) elicits a therapeutic response in both non melanoma skin cancer and immune-mediated skin disorders. Production of reactive oxygen species may result in direct cell death; however PDT-induced inflammatory and immune responses may also contribute to the therapeutic effects. The aims of my thesis were to examine for evidence of topical PDT-induced apoptosis and leucocyte trafficking, and the mechanisms underlying their mediation, in human skin.

Basal Cell Carcimona (BCC) is the most common form of skin cancer in the UK, occurring most frequently on sun exposed sites such as the head, neck and trunk and has been associated with mutations in genes expressed by keratinocytes. In particular, the mutation of the Patched receptor of the Hedgehog signalling pathway results in the up regulation of the target transcription factor GU 1. BCCs also have a complex stroma which consists of dermal fibroblasts. Dermal fibroblasts form a supportive structure through the production and release of collagens for extracellular matrices and the expression of growth factors supportive to other localised cells types. Tumour derived fibroblasts have been shown to influence the growth of other forms of epithelial cancer such as breast and prostate, conferring tumourgenic properties and effecting normal growth. However, the properties of BCCs are poorly described and this is due in part to the difficulty in culturing BCCs. The aim of this study was to develop a method for successful extraction and culture of both BCC derived keratinocytes and dermal fibroblast, characterise and study any potential stromal effects of these cells. Keratinocyte and dermal fibroblast extractions were performed on 4 mm punch biopsies. BCC derived dermal fibroblasts were grown in comparison with normal human dermal fibroblasts extracted from normal human facelift skin. A Comparison of growth between normal dermal fibroblasts and BCC derived dermal fibroblasts showed BCC derived fibroblasts senescing under normal culture conditions. Immunocytochemistry detection of Beta Galactosidase was used to confirm this, indicating that once removed from the influence of BCC epithelium, BCC derived dermal fibroblasts tended towards senescence with continued passage. Quantitative Real , Time-PCR (qPCR) showed an increase in expression levels for markers of senescence. Immunocytochemistry of GUI showed expression in both normal dermal fibroblasts and BCC derived fibroblasts therefore qPCR was performed to detect the presence of the components of the Hedgehog signalling pathway. Treatment of the cells with an inhibitor of this pathway proved ineffective in reducing the expression of GUI. Therefore the presence of GUI in the BCC derived fibroblasts suggests that paracrine signalling may be important to the maintenance of the BCC stroma and hence BCC tumour growth. However the expression of GUI may be a result of a non-canonical pathway rather than the traditional Hedgehog Pathway.

Thesis (M.S.)--Missouri University of Science and Technology, 2009.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 13, 2009) Includes bibliographical references (p. 46).

Increasing evidence has revealed that the chemokines CXCL9, CXCL10, CXCL11, and their common receptor CXCR3, are associated with tumorigenesis. Basal cell carcinoma (BCC) is a type of non-melanoma skin cancer (NMSC) and is the most common malignancy encountered. In this thesis, I hypothesized that CXCR3 signaling provides a novel marker for the growth and putative immune privilege of BCC as well as for the development of other NMSCs, such as cutaneous squamous cell carcinoma (SCC). Increased expression of chemokines CXCL10, 11 and CXCR3 was detected in cytokeratin 17 (K17)⁺ BCC cells. CXCR3/CXCL11 signaling was found to support the proliferation and survival of primary K17⁺ BCC cells derived from patient samples. Also, human BCC cells migrated in response to CXCL11 peptide in a dose-dependent manner. These findings suggest that CXCR3 signaling may be an important autocrine and/or paracrine mediator in BCC tumorigenesis. To further support the role of CXCR3 signaling in NMSC, expression of CXCR3 and its ligands were found to be significantly upregulated in cutaneous SCC and its precancerous forms (greatest in SCC). Neutralization of CXCR3 bioactivity demonstrated that CXCR3/CXCL11 signaling supported the proliferation and survival of HaCaT neoplastic keratinocyte cell cultures. Moreover, HaCaT cells transmigrated in response to CXCL11 in a dose-dependent manner. Taken together, CXCR3/ligand signaling may be important for neoplastic keratinocyte proliferation and migration, especially in cutaneous SCCs. Studies suggest BCCs exhibit immune privilege (IP), though the mechanisms have not been defined. Upregulation of a panel of IP-related genes, including IDO1, IDO2, CD200 and CD200R was identified in BCC tissues with IDO2 being expressed at the highest level. Notably, the expression and enzymatic activity of indoleamine 2,3-dioxygenase (IDO) was increased in human K17⁺ BCC cells in vitro with increased CXCR3/CXCL11 signaling. These results suggest that functional IDO is synthesized by human BCCs and may confer immunoprotection to the tumor cells, which may be enhanced by CXCR3 signaling. This thesis has revealed novel roles of CXCR3 signaling as part of the mechanism of BCC and related neoplasia development. The data may improve our understanding of NMSC pathogenesis as well as enable invention and/or modification of treatment modalities.

The human skin provides us with an excellent protective barrier and possesses a remarkable ability of constant renewal. Basal cell carcinoma is the most common type of skin cancer. The aim of this project was to verify results from an earlier study investigating the molecular differences between basal cell carcinoma (BCC) and basal cells of normal human epidermis. In that study microdissection of cell populations from BCC and basal cells of normal epidermis respectively was performed in five cases of confirmed BCC. Following RNA extraction and amplification, a gene expression analysis was performed using a 46 k human cDNA microarray. Comparison of expression profiles showed a differential expression of approximately 300 genes in BCC. An upregulation of signaling pathways previously known to be of importance in BCC development could be observed, as well as a downregulation of differentiation markers, MHC class II molecules, and proteins active in scavenging of oxygen radicals. We wanted to confirm these findings for a number of selected genes, using real time PCR. The focal point of this project was microdissection of cells from BCC and subsequent isolation of RNA. Microdissection based methods offer a possibility of selecting well defined cell populations for further analysis by using a focused laser beam. Initially tests in order to optimize the method were also performed, concerning the dehydration process and choice of slides used in microdissection. Isolation of RNA may, as we experienced, be associated with problems due to destruction of RNA by degrading enzymes.

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O carcinoma basocelular (CBC) é a neoplasia maligna mais comum entre os homens e sua incidência está aumentando em nosso meio. Pode se manifestar como lesão nodular, superficial, esclerodermiforme, micronodular e fibroepitelioma de Pinkus. O CBC é um carcinoma de baixa mortalidade, porém com elevada morbidade devido ao potencial destrutivo local e às elevadas taxas de reincidência. As diferenças evolutivas dos diversos tipos de carcinomas basocelulares não são bem definidas. A análise de fatores de proliferação e apoptose pode subsidiar o conhecimento sobre a fisiopatologia e as diferenças evolutivas dessas lesões. A literatura revela a escassez de investigações sobre a expressão diferencial de fatores de proliferação (Ki-67) e relacionados à apoptose (p53, survivina e NF-kB-p105) dos diferentes subtipos de carcinomas basocelulares e ainda tumores recidivados. O objetivo desse estudo é avaliar a expressão de marcadores de proliferação celular e apoptose em carcinomas basocelulares dos tipos nodular, superficial, esclerodermiforme e tumores recidivados. Foram selecionados subtipos histológicos únicos, como forma de tentar compreender o comportamento dos CBCs individualmente. As lâminas desses espécimes foram submetidas ao protocolo de marcação imuno-histoquímica. Foram estudadas 100 amostras, sendo 50 unidades de epiderme normal e as demais distribuídas entre cada subtipo tumoral. O padrão de marcação de cada marcador sobre os diferentes tipos de tecidos foi avaliado a partir de modelos lineares generalizados (GLMs) seguidos de teste post-hoc de Sidak, quando necessário. Foram encontradas diferenças estatisticamente significativas (p<0,01) na imunomarcação de diferentes tipos de tecidos para os marcadores Ki-67, p53 e survivina, mas não para o marcador p105 (p=0,21). O marcador Ki-67 foi mais expresso nos esclerodermiformes que em células da epiderme e nos nodulares. A imunomarcação do p53 foi menos expressa na epiderme que nos subtipos superficiais e nas recidivas, e também menos expressa nos esclerodermiformes que em todos os outros subtipos tumorais. A survivina mostrou uma imunomarcação maior na epiderme em relação aos subtipos tumorais estudados. A comparação entre os diferentes marcadores foi avaliada pelo cieficiente de correlação de Spearman, que detectou uma correlação estatisticamente significativa (p<0,01) entre os marcadores, Ki-67 e p53 na imunomarcação dos subtipos estudados e de células da epiderme, e uma correlação entre Ki-67 e survivina quando consideramos apenas as células tumorais. Neste estudo, a expressão simultânea de marcadores permitiu a identificação de padrões de proliferação e apoptose que individualizaram comportamentos em subtipos de CBCs, em consonância com formas recidivadas, e de forma independente na epiderme. Houve diferentes padrões de correlação entre a expressão dos marcadores dos CBCs e da epiderme.
Basal cell carcinoma (BCC) is the most common malignant neoplasm among men and its incidence is increasing in our country. It can manifest as nodular, superficial, sclerodermiform, micronodular and Pinkus fibroepithelioma lesions. BCC is a low-mortality carcinoma, but with high morbidity due to local destructive potential and high rates of recurrence. The evolutionary differences of the various types of basal cell carcinomas are not well defined. The analysis of proliferation and apoptosis factors may support knowledge about the pathophysiology and evolutionary differences of these lesions. The literature reveals the scarcity of investigations on the differential expression of proliferation factors (Ki-67) and related apoptosis (p53, survivin and NF-kB-p105) of the different subtypes of basal cell carcinomas and recurrent tumors. The aim of this study is to evaluate the expression of markers of cell proliferation and apoptosis in basal cell carcinomas of the nodular, superficial, sclerodermiform and recurrent tumors. Unique histological subtypes were selected as a way to attempt to understand the behavior of individual BCCs. The slides of these specimens were submitted to the immunohistochemical labeling protocol. A total of 100 samples were studied, being 50 normal epidermal units and the others distributed between each tumor subtype. The marking pattern of each marker on the different tissue types was evaluated from generalized linear models (GLMs) followed by Sidak post-hoc test, when necessary. Statiscally significant differences (p<0,01) in the immunostaining of different tissue types were found for the Ki-67, p53 and survivin markers, but not for the p105 marker (p=0,21). The Ki-67 marker was more expressed in sclerodermiform than in epidermal and nodular cells. Immunoblotting of p53 was less expressed in the epidermis than in superficial subtypes and relapses, and also less expressed in sclerodermiform than in all other tumor subtypes. Survivin showed a greater immunostaining in the epidermis with respect to the tumor subtypes studied. The comparison between the diferent markers was evaluated by the Spearman correlation coefficient, which detected a statistically significant correlation (p<0,01) between the markers, Ki-67 and p53 in the immunoblotting of the studied subtypes and epidermal cells, and one correlation between Ki-67 and survivin when we considered only tumor cells. In this study, the simultaneous expression of markers allowed the identification of patterns of proliferation and apoptosis that individualized behaviors in subtypes of BCCs, in consonance with relapsed forms, and independently in the epidermis. There were different patterns of correlation between the expression of BCC and epidermal markers.

Non-melanoma skin cancer (NMSC) is the most common cancer in the world with a lifetime risk for development as high as 2 in 3 in Queensland, Australia. Mortality is quite low, representing an approximate 360 deaths in Australia annually but cost of treatment is extremely high, estimated at $232 million each year. Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) are the two most common forms of NMSC. Although BCC generally do not have the propensity to metastasise, they are highly invasive and can be locally destructive. SCC on the other hand is invasive and has metastatic potential. SCC is generally derived from a precursor lesion, solar keratosis (SK), which is also considered to be a biomarker of BCC, SCC and malignant melanoma. According to one theory, SKs actually represent the first recognisable stage of SCC development and therefore may be indicative of the earliest stage of NMSC development. In addition to these common forms of NMSC, rarer forms such as keratoacanthoma (KA), which spontaneously regress, and SCC in situ, which rarely become invasive, may provide clues into protective mechanisms associated with prevention of development. Like all other cancers, NMSC arises from an accumulation of genetic abnormalities that result in severe cellular dysfunction. A number of genes have been proposed in the development of NMSC, including p53, CDKN2a, Bcl-2 and the Ras family of genes, which are typically associated with proliferative and differentiation processes. Also, a number of genetic disorders that predispose individuals to NMSC have also been identified. Genetic abnormalities in these genes may be a result of somatic mutations that may be promoted by environmental carcinogens. For NMSC, ultraviolet (UV) radiation is the primary environmental stimulus that acts upon skin to generate mutations. UV effects are 2-fold; the first being direct damage produced by UVB radiation and the second being indirect damage as a result of UVA-induced oxidative stress. In addition to mutations of genes that directly result in carcinogenesis, polymorphic variants of genes may also play a role in susceptibility to NMSC. These susceptibility genes may have immunogenic, detoxifying or transcriptional roles that could be involved in increased mutagenesis or activation of cancer causing genes. The purpose of this study was ultimately to identify further molecular based mechanisms associated with the development of non-melanoma skin cancer. Initially, this study aimed to examine the effects of aberrant chromosomal regions on NMSC development and also to identify candidate genes within these regions that may be implicated in the development and progression of NMSC. Also, based on chromosomal and functional implications, a number of candidate genes were assessed using association analysis to determine their involvement in susceptibility to the earliest stages of NMSC development. Implicated susceptibility genes were then further investigated to determine their response to UV radiation. Therefore the methodological approach of these studies was based on three broad technical applications of cytogenetic, association and expression analyses. Previous comparative genomic hybridisation (CGH) studies implicated the 18q chromosomal region in progression of SK to SCC and this region was therefore suspected of harbouring one or more tumour suppressor genes that were associated with a more malignant phenotype. Following on from this analysis, loss of heterozygosity (LOH) analysis was used for further delineation of this region and possibly to implicate candidate genes involved in progression. Additionally, CGH was used to investigate keratoacanthoma to determine aberrant regions that might be involved in progression and also regression of this NMSC. Genes that had potential functional roles in NMSC development and that were located in or near regions implicated by these cytogenetic analyses were further investigated using association analysis. Association analysis was performed using polymerase chain reaction and subsequent restriction enzyme digestion or GeneScan analysis to determine genotype and allele frequencies in an SK affected versus control population for polymorphisms within a number of candidate genes. This population was carefully phenotyped so that not only genotypic factors could be analysed but also their interaction with a number of phenotypic and environmental risk factors. Genes with polymorphisms that did show association with solar keratosis development were then examined functionally. Specifically, gene expression analysis was undertaken to investigate their response to UV radiation. Both UVA only and combined UVA/UVB treatments were used for short term irradiation and also for long term irradiation with recovery to determine differential effects of UV range and dose in human skin. Relative mRNA expression analysis of these genes was performed using quantitative real time reverse transcription polymerase chain reaction to determine if UV radiation imposed gene expression changes in the skin. A combination of these methodologies provided a wide basis for investigation of NMSC. Cytogenetic, association and expression analyses all allow for the identification of molecular risk factors that cause or are associated with NMSC development and progression. These analyses provided diverse results that implicated various molecular mechanisms in the development of NMSC. Cytogenetic analysis is a powerful technique, especially for the identification of a broad range of aberrations throughout the genome. This study employed LOH analysis to investigate an implicated region involved in progression to SCC and to attempt identification of candidate genes that may be involved in this process. LOH analysis was successfully performed on 9 SCCs, 5 SCCs in situ and 2 SKs using 8 microsatellite markers within the 18q region. Polymerase chain reaction (PCR) was used to amplify polymorphic regions of these markers and genotypic composition was determined for normal and cancerous tissue within the specimen. In heterozygote individuals, determined by analysis of normal tissue, the cancerous tissue was examined to determine if alleles within the implicated region had been lost. However, after analysis of multiple different samples, there was no LOH detected in any of the samples examined for this analysis. This does not necessarily reject a role for 18q, or genes within this region, as the localisation of candidate tumour suppressor genes within a small region may indicate a tighter region of involvement than was expected. As such, a more targeted study may further delineate this region and implicate candidate genes in progression of SK to the more malignant phenotype of SCC. Further CGH analysis of keratoacanthoma was also undertaken to identify aberrations associated with development and also regression of this skin cancer. CGH was performed using universal amplification and nick translation to incorporate a fluorescent dye. Differentially labelled normal and tumour DNA were then competitively hybridised to a normal metaphase spread and fluorescence emission indicated either amplification or deletion of specific chromosomal regions. In total, 6 KA samples were analysed, with 2 samples each from evolving, matured and regressing stages of KA development. In general, regressing KAs appeared to be more highly associated with deleted regions than evolving and matured KAs. Specifically, the 15q chromosomal region that was deleted in regressing KAs but amplified in evolving or matured KAs, may be significantly involved in the process of KA regression. Also various candidate genes that were being considered for analysis were located in or near some of these implicated regions, including GSTM1, GSTP1 and SSTR2. As such, these candidate genes were targeted for further investigation. A number of susceptibility genes that were located in or near aberrant regions implicated in NMSC development were investigated using association analysis. These genes included members of the somatostatin receptor family (SSTR1 and SSTR2), members of the glutathione-S-transferase (GST) family (GSTM1, GSTT1, GSTP1 and GSTZ1) and the vitamin D receptor (VDR). Studies detected a number of interesting interactions between genetic, environmental and phenotypic factors in the development of the early stages of non-melanoma skin cancer. Additionally, genes implicated in NMSC development were further investigated using expression analysis to determine response to UV radiation. Association analysis was initially performed on members of the somatostatin receptor family. Somatostatin is a growth inhibiting factor, amongst other things, that mediates its actions through the somatostatin receptors (SSTRs). The presence of these receptors (SSTR1-5) in tumour cells indicates a potential for somatostatin to bind and suppress growth, as well as allowing for therapeutic treatment with somatostatin analogues. Additionally, expression of these receptors in normal tissue, including skin, should allow for potential protection against tumour growth. The genes for SSTR1 and SSTR2 have been shown to contain dinucleotide repeat polymorphisms, and although these polymorphisms may not directly result in altered expression or binding potential, they may be linked to another functional polymorphism that does. Using association analysis the SSTR1 and SSTR2 genes were investigated to determine whether they play a role in the development of solar keratosis. Results showed that there were no significant differences between SSTR1 and SSTR2 polymorphism frequencies in the tested solar keratosis population (P = 0.10 and P = 0.883, respectively) as compared to an unaffected population. Hence, these studies do not support a role for the SSTR1 or SSTR2 genes in solar keratosis development. Further association analysis and subsequent expression analysis was also performed on members of the glutathione-S-transferase family. The GST enzymes play a role in the detoxification of a number of carcinogens and mutagens, including those produced by UV-induced oxidative stress. This study examined the role of GSTM1, GSTT1, GSTP1 and GSTZ1 gene polymorphisms in susceptibility to SK development. Association analysis was performed to detect allele and genotype frequency differences in SK affected and control populations using PCR and restriction enzyme digestion. No significant differences were detected in GSTP1 and GSTZ1 allele or genotype frequencies, however polymorphisms within both genes were found to be in linkage disequilibrium, as previously reported, and a new allelic variant of the GSTZ1 gene was identified. Significant associations between GSTM1 (P = 0.003) and GSTT1 (P = 0.039) genotypes and SK development were detected, with the null variants of both genes conferring an approximate 2-fold increase in risk for solar keratosis development (OR: 2.1; CI: 1.3-3.5 and OR: 2.3; CI: 1.0-5.0 for GSTM1 and GSTT1, respectively). For the GSTM1 gene, this risk was significantly higher in conjunction with high outdoor exposure (OR: 3.4; CI: 1.9-6.3) and although the GSTT1 gene showed a similar trend (OR: 2.9; CI: 1.1-7.7), this did not reach significance. The increased risk of SK development associated with these genes is likely due to a decreased ability of the skin to detoxify mutagenic compounds produced by UV-induced oxidative stress, and hence a decreased ability to protect against carcinogenesis. Implication of the GSTM1 and GSTT1 null variants in solar keratosis development prompted interest in analysis of gene expression changes in response to UV radiation. Due to the high homology of the GSTM1 gene with other GSTM genes, and therefore potential issues with primer specificity, the GSTT1 gene was focussed on for the expression studies. Real time reverse transcription PCR, incorporating SYBR green fluorescence and 18S as a comparative gene, was used to study GSTT1 gene expression changes in response to both UVA and combined UVA/UVB radiation. It was found that only short term UV radiation had an effect on GSTT1 expression changes, whereas no alteration of gene expression was seen after 4 and 12 hours of recovery from long term irradiation between irradiated and matched non-irradiated skin samples. This indicated that changes in gene expression for the GSTT1 gene apparently occur relatively quickly after exposure to UV radiation. Analysis of both UVA only and combined UVA/UVB short term irradiation indicated that an initial decrease in expression, followed by an increase was likely to represent translation into protein and subsequent transcription of mRNA, and in some cases a second decrease indicated further translation. Hence, it appears as though UV radiation does have a significant effect on the expression of at least one GST gene, and that UV radiation in combination with genetic variation of these genes may play a role in the development of NMSC. Finally, association and subsequent expression analysis was also performed on the vitamin D receptor. The hormonal form of vitamin D, 1a25 dihydroxyvitamin D3, has been shown to have numerous cancer-related effects, including antiproliferative, differentiation, proapoptotic and antiangiogenic effects. These effects are mediated through the binding of 1a25 dihydroxyvitamin D3 to the vitamin D receptor and subsequent transcriptional pathways. Polymorphisms within the VDR are known to regulate its transcription and therefore expression, which is linked to the ability of 1a25 dihydroxyvitamin D3 to bind. Association analysis of a 5’ initiation codon variant (Fok I) and two 3’ variants (Apa I and Taq I) was performed in SK affected and control populations. Although the Fok I variant showed no association with SK development, both the Apa I and Taq I variants were found to be associated with SK development (P = 0.043 and P = 0.012, respectively). In particular, the Aa and Tt genotypes were associated with increased risk of SK. These results were however more complicated, as shown by further analysis. This showed that genotypes containing at least one allele that conferred decreased VDR transcription (ie. AA/Aa and Tt/tt) increased risk of SK development by 2-fold in fair skinned individuals (OR: 2.1; CI: 1.2-3.7 and OR: 1.7; CI: 1.1-2.7 for Apa I and Taq I variants, respectively) but also found to decrease the risk of SK development by 2-fold in medium skinned individuals (OR: 0.5; CI: 0.3-1.0 for Apa I variants). Additionally, genotypes containing 2 alleles conferring decreased transcription of the VDR gene were found to further increase the risk for SK development in fair skinned individuals (OR: 2.5; CI: 1.4-4.5 and OR: 2.4; CI: 1.2-5.0 for Apa I and Taq I variants, respectively), indicating a possible additive effect for the alleles. The highly differential association of the VDR gene polymorphisms amongst phenotypes may reflect a combination between the ability of an individual to synthesise 1a25 dihydroxyvitamin D3 with the binding availability of the VDR. To further investigate the role of VDR in NMSC, expression analysis of the VDR gene was undertaken using real time reverse transcription PCR, with SYBR green fluorescence and 18S as a comparative gene, to examine expression pattern changes associated with UV radiation. It was found that short term irradiation, as well as long term irradiation and recovery were associated with gene expression changes. Short term irradiation resulted in patterns indicative of translation and subsequent transcription, whereas long term irradiated samples resulted in reduction of VDR expression that was recovered after an extended period of time. Thus, VDR expression is clearly influenced by UV exposure. It would be very interesting to see more specifically if particular VDR genotypes, which appear to play a role in NMSC risk, also are affected differentially by UV exposure. It is possible that VDR expression is reduced to limit excessive binding of 1a25 dihydroxyvitamin D3, although since both UVA and UVB radiation affect VDR expression, this may not be mediated the effect of 1a25 dihydroxyvitamin D3 but rather a different pathway resulting from a general UV response. In summary, the detection of a number of susceptibility genes involved in SK development and their subsequent expression analysis in response to UV radiation has given further insight into the molecular changes associated with NMSC. In fact, both detoxification genes (GSTM1 and GSTT1) and a transcription related gene (VDR), were found to confer susceptibility to solar keratosis, an early stage skin lesion with tumourigenic potential. This suggests that even the earliest stages of skin cancer are mediated through a wide range of effects. Additionally, expression changes related to these genes indicate that they are associated with the well known environmental carcinogen of UV radiation and that their effects may be mediated through a wide range of pathways. Although implication of the 18q region in SCC progression was not confirmed in this study, it is still likely to play a role in malignant transformation. The implication of this region, as well as the implication of susceptibility genes has vastly increased knowledge into processes associated with NMSC. Although additional analysis can confirm and further implicate these molecular alterations, this study has resulted in a more comprehensive understanding of NMSC that may ultimately be of benefit in terms of prognosis and treatment.

Non-melanoma skin cancer (NMSC) is the most common cancer in the world with a lifetime risk for development as high as 2 in 3 in Queensland, Australia. Mortality is quite low, representing an approximate 360 deaths in Australia annually but cost of treatment is extremely high, estimated at $232 million each year. Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) are the two most common forms of NMSC. Although BCC generally do not have the propensity to metastasise, they are highly invasive and can be locally destructive. SCC on the other hand is invasive and has metastatic potential. SCC is generally derived from a precursor lesion, solar keratosis (SK), which is also considered to be a biomarker of BCC, SCC and malignant melanoma. According to one theory, SKs actually represent the first recognisable stage of SCC development and therefore may be indicative of the earliest stage of NMSC development. In addition to these common forms of NMSC, rarer forms such as keratoacanthoma (KA), which spontaneously regress, and SCC in situ, which rarely become invasive, may provide clues into protective mechanisms associated with prevention of development. Like all other cancers, NMSC arises from an accumulation of genetic abnormalities that result in severe cellular dysfunction. A number of genes have been proposed in the development of NMSC, including p53, CDKN2a, Bcl-2 and the Ras family of genes, which are typically associated with proliferative and differentiation processes. Also, a number of genetic disorders that predispose individuals to NMSC have also been identified. Genetic abnormalities in these genes may be a result of somatic mutations that may be promoted by environmental carcinogens. For NMSC, ultraviolet (UV) radiation is the primary environmental stimulus that acts upon skin to generate mutations. UV effects are 2-fold; the first being direct damage produced by UVB radiation and the second being indirect damage as a result of UVA-induced oxidative stress. In addition to mutations of genes that directly result in carcinogenesis, polymorphic variants of genes may also play a role in susceptibility to NMSC. These susceptibility genes may have immunogenic, detoxifying or transcriptional roles that could be involved in increased mutagenesis or activation of cancer causing genes. The purpose of this study was ultimately to identify further molecular based mechanisms associated with the development of non-melanoma skin cancer. Initially, this study aimed to examine the effects of aberrant chromosomal regions on NMSC development and also to identify candidate genes within these regions that may be implicated in the development and progression of NMSC. Also, based on chromosomal and functional implications, a number of candidate genes were assessed using association analysis to determine their involvement in susceptibility to the earliest stages of NMSC development. Implicated susceptibility genes were then further investigated to determine their response to UV radiation. Therefore the methodological approach of these studies was based on three broad technical applications of cytogenetic, association and expression analyses. Previous comparative genomic hybridisation (CGH) studies implicated the 18q chromosomal region in progression of SK to SCC and this region was therefore suspected of harbouring one or more tumour suppressor genes that were associated with a more malignant phenotype. Following on from this analysis, loss of heterozygosity (LOH) analysis was used for further delineation of this region and possibly to implicate candidate genes involved in progression. Additionally, CGH was used to investigate keratoacanthoma to determine aberrant regions that might be involved in progression and also regression of this NMSC. Genes that had potential functional roles in NMSC development and that were located in or near regions implicated by these cytogenetic analyses were further investigated using association analysis. Association analysis was performed using polymerase chain reaction and subsequent restriction enzyme digestion or GeneScan analysis to determine genotype and allele frequencies in an SK affected versus control population for polymorphisms within a number of candidate genes. This population was carefully phenotyped so that not only genotypic factors could be analysed but also their interaction with a number of phenotypic and environmental risk factors. Genes with polymorphisms that did show association with solar keratosis development were then examined functionally. Specifically, gene expression analysis was undertaken to investigate their response to UV radiation. Both UVA only and combined UVA/UVB treatments were used for short term irradiation and also for long term irradiation with recovery to determine differential effects of UV range and dose in human skin. Relative mRNA expression analysis of these genes was performed using quantitative real time reverse transcription polymerase chain reaction to determine if UV radiation imposed gene expression changes in the skin. A combination of these methodologies provided a wide basis for investigation of NMSC. Cytogenetic, association and expression analyses all allow for the identification of molecular risk factors that cause or are associated with NMSC development and progression. These analyses provided diverse results that implicated various molecular mechanisms in the development of NMSC. Cytogenetic analysis is a powerful technique, especially for the identification of a broad range of aberrations throughout the genome. This study employed LOH analysis to investigate an implicated region involved in progression to SCC and to attempt identification of candidate genes that may be involved in this process. LOH analysis was successfully performed on 9 SCCs, 5 SCCs in situ and 2 SKs using 8 microsatellite markers within the 18q region. Polymerase chain reaction (PCR) was used to amplify polymorphic regions of these markers and genotypic composition was determined for normal and cancerous tissue within the specimen. In heterozygote individuals, determined by analysis of normal tissue, the cancerous tissue was examined to determine if alleles within the implicated region had been lost. However, after analysis of multiple different samples, there was no LOH detected in any of the samples examined for this analysis. This does not necessarily reject a role for 18q, or genes within this region, as the localisation of candidate tumour suppressor genes within a small region may indicate a tighter region of involvement than was expected. As such, a more targeted study may further delineate this region and implicate candidate genes in progression of SK to the more malignant phenotype of SCC. Further CGH analysis of keratoacanthoma was also undertaken to identify aberrations associated with development and also regression of this skin cancer. CGH was performed using universal amplification and nick translation to incorporate a fluorescent dye. Differentially labelled normal and tumour DNA were then competitively hybridised to a normal metaphase spread and fluorescence emission indicated either amplification or deletion of specific chromosomal regions. In total, 6 KA samples were analysed, with 2 samples each from evolving, matured and regressing stages of KA development. In general, regressing KAs appeared to be more highly associated with deleted regions than evolving and matured KAs. Specifically, the 15q chromosomal region that was deleted in regressing KAs but amplified in evolving or matured KAs, may be significantly involved in the process of KA regression. Also various candidate genes that were being considered for analysis were located in or near some of these implicated regions, including GSTM1, GSTP1 and SSTR2. As such, these candidate genes were targeted for further investigation. A number of susceptibility genes that were located in or near aberrant regions implicated in NMSC development were investigated using association analysis. These genes included members of the somatostatin receptor family (SSTR1 and SSTR2), members of the glutathione-S-transferase (GST) family (GSTM1, GSTT1, GSTP1 and GSTZ1) and the vitamin D receptor (VDR). Studies detected a number of interesting interactions between genetic, environmental and phenotypic factors in the development of the early stages of non-melanoma skin cancer. Additionally, genes implicated in NMSC development were further investigated using expression analysis to determine response to UV radiation. Association analysis was initially performed on members of the somatostatin receptor family. Somatostatin is a growth inhibiting factor, amongst other things, that mediates its actions through the somatostatin receptors (SSTRs). The presence of these receptors (SSTR1-5) in tumour cells indicates a potential for somatostatin to bind and suppress growth, as well as allowing for therapeutic treatment with somatostatin analogues. Additionally, expression of these receptors in normal tissue, including skin, should allow for potential protection against tumour growth. The genes for SSTR1 and SSTR2 have been shown to contain dinucleotide repeat polymorphisms, and although these polymorphisms may not directly result in altered expression or binding potential, they may be linked to another functional polymorphism that does. Using association analysis the SSTR1 and SSTR2 genes were investigated to determine whether they play a role in the development of solar keratosis. Results showed that there were no significant differences between SSTR1 and SSTR2 polymorphism frequencies in the tested solar keratosis population (P = 0.10 and P = 0.883, respectively) as compared to an unaffected population. Hence, these studies do not support a role for the SSTR1 or SSTR2 genes in solar keratosis development. Further association analysis and subsequent expression analysis was also performed on members of the glutathione-S-transferase family. The GST enzymes play a role in the detoxification of a number of carcinogens and mutagens, including those produced by UV-induced oxidative stress. This study examined the role of GSTM1, GSTT1, GSTP1 and GSTZ1 gene polymorphisms in susceptibility to SK development. Association analysis was performed to detect allele and genotype frequency differences in SK affected and control populations using PCR and restriction enzyme digestion. No significant differences were detected in GSTP1 and GSTZ1 allele or genotype frequencies, however polymorphisms within both genes were found to be in linkage disequilibrium, as previously reported, and a new allelic variant of the GSTZ1 gene was identified. Significant associations between GSTM1 (P = 0.003) and GSTT1 (P = 0.039) genotypes and SK development were detected, with the null variants of both genes conferring an approximate 2-fold increase in risk for solar keratosis development (OR: 2.1; CI: 1.3-3.5 and OR: 2.3; CI: 1.0-5.0 for GSTM1 and GSTT1, respectively). For the GSTM1 gene, this risk was significantly higher in conjunction with high outdoor exposure (OR: 3.4; CI: 1.9-6.3) and although the GSTT1 gene showed a similar trend (OR: 2.9; CI: 1.1-7.7), this did not reach significance. The increased risk of SK development associated with these genes is likely due to a decreased ability of the skin to detoxify mutagenic compounds produced by UV-induced oxidative stress, and hence a decreased ability to protect against carcinogenesis. Implication of the GSTM1 and GSTT1 null variants in solar keratosis development prompted interest in analysis of gene expression changes in response to UV radiation. Due to the high homology of the GSTM1 gene with other GSTM genes, and therefore potential issues with primer specificity, the GSTT1 gene was focussed on for the expression studies. Real time reverse transcription PCR, incorporating SYBR green fluorescence and 18S as a comparative gene, was used to study GSTT1 gene expression changes in response to both UVA and combined UVA/UVB radiation. It was found that only short term UV radiation had an effect on GSTT1 expression changes, whereas no alteration of gene expression was seen after 4 and 12 hours of recovery from long term irradiation between irradiated and matched non-irradiated skin samples. This indicated that changes in gene expression for the GSTT1 gene apparently occur relatively quickly after exposure to UV radiation. Analysis of both UVA only and combined UVA/UVB short term irradiation indicated that an initial decrease in expression, followed by an increase was likely to represent translation into protein and subsequent transcription of mRNA, and in some cases a second decrease indicated further translation. Hence, it appears as though UV radiation does have a significant effect on the expression of at least one GST gene, and that UV radiation in combination with genetic variation of these genes may play a role in the development of NMSC. Finally, association and subsequent expression analysis was also performed on the vitamin D receptor. The hormonal form of vitamin D, 1a25 dihydroxyvitamin D3, has been shown to have numerous cancer-related effects, including antiproliferative, differentiation, proapoptotic and antiangiogenic effects. These effects are mediated through the binding of 1a25 dihydroxyvitamin D3 to the vitamin D receptor and subsequent transcriptional pathways. Polymorphisms within the VDR are known to regulate its transcription and therefore expression, which is linked to the ability of 1a25 dihydroxyvitamin D3 to bind. Association analysis of a 5Â’ initiation codon variant (Fok I) and two 3Â’ variants (Apa I and Taq I) was performed in SK affected and control populations. Although the Fok I variant showed no association with SK development, both the Apa I and Taq I variants were found to be associated with SK development (P = 0.043 and P = 0.012, respectively). In particular, the Aa and Tt genotypes were associated with increased risk of SK. These results were however more complicated, as shown by further analysis. This showed that genotypes containing at least one allele that conferred decreased VDR transcription (ie. AA/Aa and Tt/tt) increased risk of SK development by 2-fold in fair skinned individuals (OR: 2.1; CI: 1.2-3.7 and OR: 1.7; CI: 1.1-2.7 for Apa I and Taq I variants, respectively) but also found to decrease the risk of SK development by 2-fold in medium skinned individuals (OR: 0.5; CI: 0.3-1.0 for Apa I variants). Additionally, genotypes containing 2 alleles conferring decreased transcription of the VDR gene were found to further increase the risk for SK development in fair skinned individuals (OR: 2.5; CI: 1.4-4.5 and OR: 2.4; CI: 1.2-5.0 for Apa I and Taq I variants, respectively), indicating a possible additive effect for the alleles. The highly differential association of the VDR gene polymorphisms amongst phenotypes may reflect a combination between the ability of an individual to synthesise 1a25 dihydroxyvitamin D3 with the binding availability of the VDR. To further investigate the role of VDR in NMSC, expression analysis of the VDR gene was undertaken using real time reverse transcription PCR, with SYBR green fluorescence and 18S as a comparative gene, to examine expression pattern changes associated with UV radiation. It was found that short term irradiation, as well as long term irradiation and recovery were associated with gene expression changes. Short term irradiation resulted in patterns indicative of translation and subsequent transcription, whereas long term irradiated samples resulted in reduction of VDR expression that was recovered after an extended period of time. Thus, VDR expression is clearly influenced by UV exposure. It would be very interesting to see more specifically if particular VDR genotypes, which appear to play a role in NMSC risk, also are affected differentially by UV exposure. It is possible that VDR expression is reduced to limit excessive binding of 1a25 dihydroxyvitamin D3, although since both UVA and UVB radiation affect VDR expression, this may not be mediated the effect of 1a25 dihydroxyvitamin D3 but rather a different pathway resulting from a general UV response. In summary, the detection of a number of susceptibility genes involved in SK development and their subsequent expression analysis in response to UV radiation has given further insight into the molecular changes associated with NMSC. In fact, both detoxification genes (GSTM1 and GSTT1) and a transcription related gene (VDR), were found to confer susceptibility to solar keratosis, an early stage skin lesion with tumourigenic potential. This suggests that even the earliest stages of skin cancer are mediated through a wide range of effects. Additionally, expression changes related to these genes indicate that they are associated with the well known environmental carcinogen of UV radiation and that their effects may be mediated through a wide range of pathways. Although implication of the 18q region in SCC progression was not confirmed in this study, it is still likely to play a role in malignant transformation. The implication of this region, as well as the implication of susceptibility genes has vastly increased knowledge into processes associated with NMSC. Although additional analysis can confirm and further implicate these molecular alterations, this study has resulted in a more comprehensive understanding of NMSC that may ultimately be of benefit in terms of prognosis and treatment.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Health Sciences
Full Text

Le carcinome basocellulaire (CBC) est le cancer le plus fréquent chez l’homme et est à lui seulresponsable de plus de cas que l’incidence cumulée de tous les autres cancers réunis. Des travauxrécents qui se sont intéressés aux étapes précoces de la tumorigenèse ont fourni un supportprécieux pour l’analyse du développement tumoral précoce. Ils ont mis en évidence le rôlecentral de gènes impliqués dans les progéniteurs embryonnaires des cellules souches du folliculepileux. Dans ce travail, nous avons étudié le rôle du facteur de transcription Sox9, un gène connupour être crucial dans la spécification de ces progéniteurs et dans les cellules souches du folliculepileux. Nous avons montré que Sox9 est requis pour la progression des lésions paranéoplasiquesvers les CBC et qu’il était également requis pour la maintenance des cellules cancéreuses. Enutilisant des méthodes d’analyse génomique de pointe, nous avons montré que Sox9 agit tantcomme un activateur que comme un répresseur de la transcription. Nous avons montré qu’ilpromeut directement le renouvellement cellulaire, l’invasion ainsi que la quiescence des cellulescancéreuses.Dans la seconde partie de ce travail, nous avons découvert le mécanisme d’action de l’inhibiteurd’Hedgehog Vismodegib sur les cellules cancéreuses. En utilisant des modèles génétiques desouris, nous avons montré que l’inhibiteur empêche la reprogrammation embryonnaire qui anormalement lieu durant la formation du CBC et qu’il promeut la différentiation des cellulescancéreuses vers une identité interfolliculaire, d’infundibulum ou sébacée suivant l’origine de cescellules. Nous avons également observé qu’une population caractérisée par l’expression du gèneLgr5 ainsi que par une activation de la voie de signalisation Wnt est plus résistante au Vismodegibchez la souris et nous avons trouvé des indices suggérant qu’il pourrait en être de même chezl’humain. Enfin, nous avons pu montrer que l’inhibition combinée des voies de signalisation Wntet Hedgehog annihile cette résistance et résulte en la disparition complète des CBCs.
Doctorat en Sciences biomédicales et pharmaceutiques (Médecine)
info:eu-repo/semantics/nonPublished

Non-melanoma skin cancer (NMSC), comprised of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), is the most common cancer in Caucasians. Ultraviolet radiation (UVR) exposure is the most important environmental risk factor for both BCC and SCC development. However, the precise relationship between UVR and the risk of NMSC is complex, and the relationship may differ by skin cancer type. It has been hypothesized that intermittent patterns and childhood sunlight exposure are important for BCC while continuous (chronic) and lifelong (i.e. childhood and adulthood) sunlight exposure is important for SCC. Epidemiologic studies have demonstrated that cutaneous human papillomavirus (HPV) infection may also be a risk factor for developing NMSC. However, the pathway by which cutaneous HPV is associated with NMSC remains unclear. It is hypothesized that UVR exposure may interact synergistically with cutaneous HPV in NMSC development. The goal of the research study was to evaluate the relationship between levels of sunlight exposure and BCC and SCC and to investigate differences in sunlight-associated BCC and SCC risk by genus-specific cutaneous HPV serostatus. To address these goals, we conducted a clinic based case-control study of histologically confirmed BCC and SCC cases recruited from a university dermatology clinic and controls with no history of cancer and screened negative for current skin cancer. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) for the associations between measures of sunlight exposure and BCC and SCC. Multiplicative interactions were tested by placing an interaction term for the product of genus-specific HPV seroreactivity and sunlight related factors in the logistic regression models. Measures of both intermittent and continuous patterns of sunlight exposure were associated with both types of skin cancer (i.e. BCC and SCC). Specifically, history of blistering sunburn (a marker of intermittent sunlight exposure) and occupational sunlight exposure (i.e. having a job in the sun for at least 3 months for >10 years) were both associated with BCC and SCC. The major differences in patterns of sunlight exposure between BCC and SCC were observed for sunlight exposure in one's thirties. Additionally, sunlight exposure in one's twenties was associated with SCC, regardless of pattern of exposure; similar associations were not observed for BCC. Measures of timing of sunlight exposure consistently demonstrated that childhood/adolescent sunlight exposure was more important for SCC than BCC. These included number of moles on the forearms and entire body (measure of increased childhood sunlight exposure), and younger age at first and tanning bed use. Younger age at first blistering sunburn was statistically significantly associated with both BCC and SCC. NMSC cases were more likely to be seropositive for cutaneous HPV antibodies compared to controls. Compared to tanning, having a propensity to sun burn (p=0.006), or poor tanning ability (p=0.003) were significantly associated with a higher seroprevalence to genus beta HPV types within SCC cases. Statistically significant interactions were observed between poor tanning ability and genus-specific seropositivity with NMSC. Specifically, the associations between poor tanning ability and BCC (p interaction=0.02) and SCC (p interaction=0.01) were significantly stronger among individuals that were seropositive for antibodies to genus alpha HPV types. Similarly, the association between poor tanning ability and SCC was stronger among those seropositive for genus beta HPV types (p interaction=0.001). No additional significant interactions were observed for BCC or SCC between cutaneous sensitivity, history of blistering sunburn, or cumulative sunlight exposure and genus-specific seroreactivity. In conclusion, associations with patterns of sunlight exposure appeared to be similar between BCC and SCC cases. With the exception of age at first blistering sunburn, factors measuring timing of sunlight exposure demonstrated stronger and statistically significant relationships with SCC. Additionally, of the sunlight related factors measured, only the associations between poor tanning ability and BCC and SCC were significantly modified by HPV seropositivity to types in genera alpha or beta.

Basal Cell Carcinoma (BCC) is the most common type of skin cancer; its development is associated with mutational inactivation of the PTCH1 tumour suppressor gene leading to deregulation of the Hedgehog pathway through increased expression of the downstream GLI (GLI1 and GLI2) transcription factors. The high expression of GLI1 and GLI2 has also been shown to be maintained through a positive feedback mechanism in human keratinocytes, but this has partly relied upon mRNA expression and has not been fully explored at the protein level. Moreover, expression analysis in human BCCs has largely relied upon in situ hybridization or RT-PCR and no studies have investigated co-expression of the GLI1 and GLI2 proteins. Whereas an active mutant of GLI2 (GLI2DN) has been shown to increase endogenous GLI1 protein expression in normal human keratinocytes, preliminary evidence suggests that ectopic GLI1 suppresses endogenous GLI2 protein expression, which refutes the presence of a positive GLI feedback loop. In human BCC samples, there was a relatively high degree of heterogeneity in the expression pattern of GLI1 and GLI2 with the various antibodies employed and this was also affected by how the tissue was processed i.e. frozen versus formalin-fixed. Surprisingly, many BCCs displayed strong epidermal GLI1 expression that was decreased in the basal layer and tumour islands. In most tumours GLI1 and GLI2 showed areas of co-expression, but this was not uniform and in many areas one protein was more abundant than the other. Moreover, there was no clear difference in the expression level of GLI1 or GLI2 between BCC subtypes (aggressive versus non-aggressive). Finally, one antibody (GLI1 H-300) detected strong GLI1 expression in mesenchymal cells surrounding tumour islands (in frozen samples) but this did not correlate with epithelial Sonic Hedgehog ligand expression, suggesting a lack of paracrine Hedgehog signalling in BCC biology. In summary, this project has shown that GLI regulation and expression are more complex than previous studies have suggested and that research in this field is hampered by a lack of consistency and reliability of commercial GLI antibodies.

Embryonic development is regulated by a number of signalling pathways, which are critical for normal growth. Many of these genes then continue to play an important role in the regulation of cell growth and differentiation in adult. One such pathway is the sonic hedgehog (SHH) pathway; SHH protein is secreted which binds to its receptor patched (PTCH), leading to the activation and repression of target genes via zinc-finger GLI family transcription factors. Deregulation of this pathway, leads to a number of human birth defects and diseases such as Basal Cell Carcinoma (BCC) of the skin. In transgenic mouse model systems activation of GLI1 by SHH-signalling is a key step in initiating BCC formation. However, there is limited understanding of the molecular mechanisms involved in response to hedgehog signalling and GLI activity in human BCC formation and how this pathway interacts with other pathways. The aim of this thesis was to establish in vitro and in vivo model systems to investigate the molecular events leading to BCC formation. I have shown that Gl.Il , Gi12, Gi13, PTCH, SMO and KlF4 were induced and a-TUB was repressed in BCC relative to normal skin. Using an in vitro model I further showed that Gl.ll , Gi12, Gi13, PTCH, SMO and a-TUB were induced and KlF4 was repressed in GLII expressing keratinocytes. Collaborative work with Dr Fritz Aberger's laboratory in Salzburg showed that Gl.Il and FOXEI are direct targets of GLI2 and I showed that Gl.I? and FOXEI were expressed in the interfollicular epidermis and the outer root sheath of hair follicles in normal skin as well as in BCC tumour islands suggesting a possible link between hair follicle and BCe. I further showed that epidermal growth factor (EGF) signalling reduces transcription activity of GLI1 by shuttling GLII out of nucleus and altering the expression of PTCH, SMO, Gil2 and Gl.B SHH genes. In addition, I demonstrated that whilst EGF induced Vimentin and Snail2 expression and GLII repressed their expression suggesting that GLI is able to counter epithelial-mesenchymal transition associated with EGF and this may in part explain why Bee very rarely metastasise. Furthermore, GLI1 appears to upregulate stem cell like signature and EGF downregulates this signature. Finally, we were able to generate a KRTI4- Floxed-GFP-Gill transgenic mouse but were unable to activate the target gene (KRTI4-GFP-GiIl). In conclusion, I have identified possible targets of GLI activity and shown interactions between EGF signalling and GLI that will help us to understand the potential molecular actions of SHH signalling with the goal of developing better therapeutic strategies.

Basal-like tumor is an aggressive breast carcinoma subtype that displays an expression signature similar to that of the basal/myoepithelial cells of the breast tissue. Basal-like carcinoma are characterized by over-expression of the Epidermal Growth Factor receptor (EGFR), high frequency of p53 mutations, cytoplasmic/nuclear localization of beta-catenin, overexpression of the Hypoxia inducible factor (HIF)-1alpha target Carbonic Anhydrase isoenzime 9 (CA9) and a gene expression pattern similar to that of normal and cancer stem cells, including the over-expression of the mammary stem cell markers CD44. In this study we investigated the role of p53, EGFR, beta-catenin and HIF-1alpha in the regulation of stem cell features and genes associated with the basal-like gene expression profile. The findings reported in this investigation indicate that p53 inactivation in ductal breast carcinoma cells leads to increased EGFR mRNA and protein levels. In our experimental model, EGFR overexpression induces beta-catenin cytoplasmatic stabilization and transcriptional activity and, by that, leads to increased aggressive features including mammosphere (MS) forming and growth capacity, invasive potential and overexpression of the mammary stem cell gene CD44. Moreover we found that EGFR/beta-catenin axis promotes hypoxia survival in breast carcinoma cells via increased CA9 expression. Indeed beta-catenin positively regulates CA9 expression upon hypoxia exposure. Interestingly we found that beta-catenin inhibits HIF-1alpha transcriptional activity. Looking for the mechanism, we found that CA9 expression is promoted by HIF-1alpha and cytoplasmatic beta-catenin further increased it post-transcriptionally, via direct mRNA binding and stabilization. These data reveal a functional beta-catenin/HIF-1alpha interplay among hallmarks of basal-like tumors and unveil a new functional role for cytoplasmic beta-catenin in the phenotype of such tumors. Therefore it can be proposed that the interplay here described among EGFR/beta-catenin and HIF-1alpha may play a role in breast cancer stem cell survival and function.

Basal-like tumor is an aggressive breast carcinoma subtype that displays an expression signature similar to that of the basal/myoepithelial cells of the breast tissue. Basal-like carcinoma are characterized by over-expression of the Epidermal Growth Factor receptor (EGFR), high frequency of p53 mutations, cytoplasmic/nuclear localization of beta-catenin, overexpression of the Hypoxia inducible factor (HIF)-1alpha target Carbonic Anhydrase isoenzime 9 (CA9) and a gene expression pattern similar to that of normal and cancer stem cells, including the over-expression of the mammary stem cell markers CD44. In this study we investigated the role of p53, EGFR, beta-catenin and HIF-1alpha in the regulation of stem cell features and genes associated with the basal-like gene expression profile. The findings reported in this investigation indicate that p53 inactivation in ductal breast carcinoma cells leads to increased EGFR mRNA and protein levels. In our experimental model, EGFR overexpression induces beta-catenin cytoplasmatic stabilization and transcriptional activity and, by that, leads to increased aggressive features including mammosphere (MS) forming and growth capacity, invasive potential and overexpression of the mammary stem cell gene CD44. Moreover we found that EGFR/beta-catenin axis promotes hypoxia survival in breast carcinoma cells via increased CA9 expression. Indeed beta-catenin positively regulates CA9 expression upon hypoxia exposure. Interestingly we found that beta-catenin inhibits HIF-1alpha transcriptional activity. Looking for the mechanism, we found that CA9 expression is promoted by HIF-1alpha and cytoplasmatic beta-catenin further increased it post-transcriptionally, via direct mRNA binding and stabilization. These data reveal a functional beta-catenin/HIF-1alpha interplay among hallmarks of basal-like tumors and unveil a new functional role for cytoplasmic beta-catenin in the phenotype of such tumors. Therefore it can be proposed that the interplay here described among EGFR/beta-catenin and HIF-1alpha may play a role in breast cancer stem cell survival and function.

Basal-like breast cancer represents a subgroup of mammary cancers associated with a particularly poor prognosis, as they are refractory to current targeted therapies employed for the treatment of breast cancer. In this work I aimed to explore the therapeutic potential of selective estrogen receptor modulators (SERMs), a targeted breast cancer treatment, in combination with epigallocatechin gallate (EGCG), for the treatment of basal-like breast cancer, using MDA-MB-231 cell as an in vitro model of the disease. A significant reduction in MDA-MB-231 cell number and a significant increase in cytotoxicity was observed following treatment with 25 [mu]M of EGCG in combination with 1 [mu]M of 4-hydroxytamoxifen (4-OHT) (EGCG+4-OHT) or 4 [mu]M of raloxifene (EGCG+Ral) over a 36 h time course. However, these effects were not resolved in time, with an increase in G₁-phase cell cycle arrest. Changes in the metabolism of EGCG were dismissed as a possible mechanism through which the combination treatments may be eliciting the cytotoxicity. Changes in the expression and phosphorylation of various signaling proteins, important for the proliferation and survival of basal-like breast cancer, were investigated through Western blotting. Interestingly, the two combination treatments produced very similar results; reductions in the phosphorylation of EGFR and AKT occurred after 6, 12, and 18 h with EGCG+4-OHT and 6, 12, 18 and 24 h with EGCG+Ral, while a reduction in S6K phosphorylation was observed following 6, 12, 18 and 24 h of both combination treatments. Interestingly, both SERMs contributed significantly to the net reduction in S6K phosphorylation, induced by the combination treatments. Both combination treatments were also associated with a significant increase in the phosphorylation and total expression of stress activated protein kinases, p38 and JNK1/2 following 12, 18 and 24 h of treatment. As changes were observed at an intracellular signaling level, the effect of the combination treatments were investigated at the transcriptomic level after 18 h of treatment, using human oligonucleotide microarrays. This transcriptomic analysis revealed that both combination treatments reduced the transcript expression of five enzymes involved with cholesterol synthesis, which was confirmed through qRT-PCR. Cholesterol is an important component of the plasma membrane and is critical for the transduction of extracellular signals. Furthermore, both combination treatments induced the transcriptomic expression of the zinc coordinating metallothionein (MT) proteins. This was associated with an increased nuclear localization of MTF-1, the transcription factor responsible for MT expression, after 6, 12 and 18 h of both combination treatments. Finally, nuclear Western blotting of the NF-[kappa]B subunit, p65, revealed that both combination treatments reduced the nuclear localization of NF-[kappa]B following 6, 12 and 18 h. In collating this data, it appears that the combination treatments of EGCG+4-OHT and EGCG+Ral are inducing cytotoxicity through various mechanisms, including reduced cellular signaling through EGFR, AKT and S6K, increased stress signaling through JNK1/2 and p38 and altered gene expression of MTs and enzymes involved with cholesterol synthesis. Therefore, the combination treatment of EGCG+SERMs exhibits therapeutic potential in MDA-MB-231 cells, a model of basal-like breast cancer.

Exposure to ultraviolet radiation and immunosuppression are the principal causes of non-melanoma skin cancer (NMSC). One of the skin’s main functions is to act as a barrier against environmental insults and transepidermal water loss (TEWL) is a marker of skin barrier function. Previous phase 2 studies have shown nicotinamide (NAM) to reduce premalignant actinic keratoses. Topical NAM has been shown to reduce TEWL. The effects of oral NAM were evaluated in two clinical trials. The Oral Nicotinamide To Reduce Actinic Cancer (ONTRAC) study was a multicentre phase 3, double-blind, randomised controlled trial in 386 immune-competent participants with at least 2 NMSCs in the past 5 years. Participants were randomised to receive 500mg of NAM or placebo twice daily for 12 months, with assessment at 3-monthly intervals for 18 months. TEWL measurements were taken 3-monthly for 12 months in 292 participants at a single study site. The primary end point was the number of new histologically-confirmed NMSCs during the 12-month intervention period. A second, phase 2 pilot study was undertaken in 22 immunosuppressed renal transplant recipients who were randomised to receive 500mg of NAM or placebo twice daily for 6 months, with assessments at 2-monthly intervals. The ONTRAC study found a 23% relative rate reduction in new NMSCs in the NAM group compared to the placebo group (p=0.02). The estimated relative reduction in TEWL with NAM at 12 months was 6% on the forehead (p=0.04) and 8% on the limbs (p=0.04). The nicotinamide renal transplant pilot study found new NMSCs to be 35% lower in the NAM group than the placebo group (p=0.4). Oral NAM was well-tolerated and safe. The work described in this thesis provides evidence that NAM is a new chemopreventive agent for NMSC in high-risk immune-competent patients. Phase 3 studies are now warranted in immunosuppressed organ transplant recipients. Nicotinamide is also a potential new systemic agent for improving skin barrier function.

O carcinoma basocelular (CBC) é uma neoplasia cutânea maligna de baixo potencial metastatizante, originada das células da camada basal da epiderme. Sua importância clínico-epidemiológica pode ser constatada pelo fato de constituir a neoplasia maligna mais comum na espécie humana, cujo principal fator etiológico é a exposição à radiação ultravioleta. Apesar da baixa incidência de metástases, a neoplasia pode adotar um comportamento localmente agressivo, com comprometimento de estruturas profundas e de forte apelo estético, como ocorre na região periocular. Uma das complicações advindas de sua infiltração neste sítio anatômico consiste na invasão de tecidos orbitários cujo tratamento é a exenteração, conduta mutiladora que consiste na retirada do globo ocular e das partes moles da órbita acometida. O objetivo deste estudo foi avaliar os casos de CBC com invasão orbitária que foram submetidos à exenteração no Hospital de Clínicas de Ribeirão Preto, no período de 1992 a 2012, para a possível identificação de fatores clínicos e morfológicos que possam predizer uma evolução desfavorável da neoplasia. Foi realizada uma coleta de dados clínicos, epidemiológicos e histopatológicos dos casos submetidos à exenteração a partir dos prontuários médicos dos pacientes. As lâminas referentes aos exames anátomo-patológicos foram revistas e foi realizado estudo imuno-histoquimico para os marcadores p53, bcl-2, actina de músculo liso e metaloproteinase-1. O grupo controle foi composto por pacientes com diagnóstico da neoplasia em topografia periocular, sem sinais de invasão orbitária. Para os casos com invasão orbitária o número de casos positivos marcados para p53 (0,21) e para actina de músculo liso (0,21) foi significantemente menor que o número de casos positivos para bcl-2 (0,63) e MMP-1 (0,58) (p= 0,0331). Entretanto, o número de casos positivos para bcl-2 (0,63) foi significantemente maior que o número de casos marcados por MMP-1 (0,58) (p=0,0126). Para os tumores sem invasão orbitária, o número de casos positivos para p53 (0,31) e actina (0,31) foi significantemente menor que o número de casos positivos para bcl-2 (0,63) eMMP-1 (0,50) (p=0,0273). Os resultados indicam que a invasão orbitaria por carcinoma basocelular palpebral ocorre com maior frequência no sexo masculino, em pacientes com longa história clínica de múltiplas lesões e submetidos a múltiplos procedimentos. Além disso, os marcadores estudados aparentemente não podem predizer um comportamento mais agressivo do tumor.
Basal cell carcinoma (BCC) is a malignant skin cancer of low metastasizing potential originated from the basal cells of the epidermis. Its clinical and epidemiological importance is evidenced by the fact that it is the most common malignancy in humans and it has as the main etiological factor the exposure to ultraviolet radiation. Despite the low incidence of metastases, the cancer can adopt a locally aggressive behavior with involvement of deep structures and it can have a strong aesthetic appeal, as in the periocular region. One of the complications arising from its infiltration in this anatomical site consists of orbital tissue invasion whose treatment is exenteration, a mutilating procedure consisting of the removal of the eyeball and the soft tissue of the affected orbit. The aim of this study was to evaluate the cases of BCC with orbital invasion that underwent exenteration at the Clinics Hospital of Ribeirão Preto Medical School, University of Sao Paulo, from 1992 through 2012, for possible identification of clinical and morphological factors that can predict an unfavorable evolution of the tumor. The clinical data were obtained from the patients\' charts and we have reviewed all the slides from exenteration specimens and performed immunohistochemical studies with p53, bcl-2, smooth muscle actin and metalloproteinase-1(MMP-1). The control group consisted of age-matched patients with eyelid basal cell carcinomas without orbital invasion. For cases with orbital invasion the number of positive cases labeled for p53 (0.21) and actin (0.21) was significantly lower than the number of positive cases for bcl-2 (0.63) and MMP -1 (0.58) (p = 0.0331). However, the number of positive cases for bcl-2 (0.63) was significantly greater than the proportion of positive cases for MMP-1 (0.58) (p = 0.0126). For cases without orbital invasion the number of positive cases for p53 (0.31) and actin (0.31) was significantly lower than the number of positive cases for bcl-2 (0.63) and MMP-1 (0.50) (p = 0.0273), even though the number of positive cases marked for MMP-1 (0.50) was not significantly different from number of positive cases for bcl-2 (0.63) (p = 0.059). The results indicate that orbital invasion of basal cell carcinoma of the eyelid was more frequent in male sex and that the patients have usually a long history of multiple lesions and were submitted to several procedures. In addition, our results suggest these markers can not predict an aggressive behavior for basal cell carcinomas of the periocular region.